Plug & Play car: Citroën C-zero

The Citroën C-zero, the Peugeot Ion and the Mitsubishi I-Miev are twin cars that arise from the development of the latter. There are small differences, mainly related to appearance and equipment.

Exterior
The first time a C-zero is seen, it looks like a Smart merged with a Citroën C1, with a size closer to the latter.

The Citroën C-zero is 136.8 inches long, 58 inches wide and 63.3 inches high. The body of a C-zero shows a big height for its size, between a C4 (58.6 inches) and a C4 Picasso (66.1 inches). This design achieves a Cx of 0.35, as many common cars (a Toyota Prius has a 0.25 Cx and the EV1 0.19). Anyway, the drag force is obtained by an expression that includes multiplying the Cx by the front area, so small vehicles can get a lower drag force even with a higher Cx.
It has 5 doors and seats for 4 adults, with a practical layout. The space between the windshield and the front bumber is small, but there’s a hood that gives access to the 12 Volts auxiliary battery (to power accesories), the power brakes and the brake fluid and windshield washer reservoirs.

The whole volume looks very compact from outside, with the axles placed on the limits of the body and front wheels that could come from a big scooter. The windshield is quite big and there is only one wiper with double joint that turns out to be effective and quick while cleaning a wide percentage of the glass (nothing to do with those on old Citroën AX, ZX, BX...).

The small size, the general appearance and the aforementioned front wheels width promised disturbing drive feelings.

Interior
The spaciousness is the first thing that comes to mind when examining the C-zero interior, greater than expected from outside.

The central area of the dashboard fits the radio (a nav system in the loaded versions) and a group of 3 round selectors arranged on a vertical layout to control climate.

These selectors reminded me of other vehicles such as the previous generation of Toyota Yaris. In the C-zero, these selectors are not intuitive and the reading is difficult, so selecting the desired conditions needs more attention than it should. Moreover, leaving the heater or the A/C on in these cars can lead to bigger problems than the energy consumption, due to the impact of these systems on the range.

Instruments cluster is way too simple, with all the necessary items but nothing else. There is a digital speedometer on the center, surrounded by an analogic power indicator. This device is more interesting than a tachometer on an electric vehicle, because the electric motor produces a high torque in a wide range of rpm that avoids the need of shifting ratios in most models. Moreover, an analogic power indicator gives information to adapt the driving style at every moment and gives a very intuitive idea of the power created during braking compared to the power consumed during acceleration. Of course, if more power is demanded continuously, the batteries are drained in a shorter period of time. This relation is not even linear, because the electric motor works in a less efficient way when high power is demanded. The power indicator is divided in four areas: charge (energy generation during deceleration), eco (low power use), normal and power (high power use). In the city, under 30 mph, the car moves using the eco zone without becoming a moving obstacle to traffic, even facing a moderate uphill. However, when driving inter-city routes at speeds around 40-55 mph, the use of the normal zone is more frequent and there will be no option but to use the power zone when facing many uphill sections. At higher speeds, the use of the two highest zones is very common.
Going back to the interior style, there are also two small lcd monochrome screens with less than 2 inches. The one on the left shows the shifter position (P-R-N-D) and the battery charge with 16 levels. The second one is on the right and faces an excessive work load, because it shows sequentially:

total odometer
partial A odometer
partial B odometer
miles until next maintenance
predicted range

I was expecting at least a prius-like display in a car with a technology load and a price such as the C-zero. In my opinion, the instrument cluster on the Toyota is an acceptable minimum. Electric and hybrid vehicles are not only technically advanced but should also look like technically advanced. Instead of the “spaceshift-look” that many of them are using, I think this is achieved by a useful and configurable interface that allows connecting to mobile devices while keeping an attractive overall look. The most interesting proposal I’ve seen in this direction is the one made by Ford in the Fusion Hybrid, the SmartGauge system with Ecoguide. In the C-zero, however, the information is so reduced that the sensation of high tech is lower than in a Chevrolet Aveo, a much cheaper car with less technology load. Things as basic as a clock or an external thermometer were not present in the tested version of the C-zero.

Moreover, as a present to the driver, they decided that the steering wheel should not have one single button on it, except the horn. So, the screen needs to be controlled through the usual button embedded on the gauges to reset the partial odometer. That implies placing the hand into the gauges area, which can be done through the interior or the exterior of the steering wheel. As a result, changing the different parameters on the right screen while driving is somewhere between heroism and the unconsciousness.
The range prediction is probably computed using the battery charge and something like a power use moving average through the last 5 or 10 minutes. It’s common to see more than 60 miles of expected range when cruising at 40 mph with a 70% of battery. However, if a strong uphill is faced during 5 minutes, the expected range can be reduced 10 or 20 miles easily. The driver experience after some days using the car and his knowledge of the route can complement this indicator. To be fair, the predicted range is very accurate with a homogenous use and, despite there is a small energy backup for emergencies, my advice is to believe the estimation to avoid pulling over without battery.
Some details could be easily improved, for example the interior door handles, which are uncomfortable to use or the difficult to find hood opening lever (under the glove box, over the passenger feet). Interior materials quality is the usual in mainstream makers, with details in leather such as the steering wheel and the shifter.
The shifter is the key to discover that PSA group, Citroën specifically, had more to do with a badge than with a whole design. The chevron maker usually surrounds its vehicles with an innovation halo which often is translated into reinventing the wheel. For example, the shifter in the robotized manual transmissions becomes odd, even for a driver used to automatic vehicles. That’s because the traditional scheme P-R-N-D is changed to another with 3 main positions (automatic, manual and reverse) and the use in sequential mode is different to the usual, shifting up when the shifter is pulled and shifting down when it’s pressed towards the dashboard. Citroën is not the only maker doing this, but probably is the one that applies it to more features on the car. Those and many others are details which create a huge differentiation between this maker and others that usually polarizes the buyers into fans of the maker or critics.
That is not the case with the C-zero. Its classic pattern shifter and the “old-style” vehicle operation with a regular key to start are way more classic than expected. The positions B and C of the shifter in the Mitsubishi I-Miev, which will be referred later, have been suppressed on the PSA vehicles. So, there’s no need of special knowledge to drive this car. Actually, it’s simpler than traditional vehicles.

Front seats are comfortable for two adults, even if they are tall. However, the trims, the seats cushion and the general appearance fit with a vehicle of one third of the price. The rear seat fits two people with a reasonable space and height, but it’s not comfortable due to a hard cushion and too reclined position. That said, it is a car in which 4 adults can move without giving up a minimum comfort. But they cannot travel, not only because of the range, but for a tiny trunk with an important volume occupied by the charging wires in a canvas bag. As many other details, I think that a small plastic compartment embedded on a trunk side wouldn’t be so expensive and provides a much better general appearance.

I took my son in it several times and it really suprises, because the tiny trunk has space enough for a baby stroller, the wires and a big bag with the baby stuff. Moreover, a baby restraint system has space enough in any of the rear places (I think it’s not fitted with Isofix, but I’m not sure because mine doesn’t use it).

Power electronics and the electric motor coupled to a transmission to move rear wheels are placed under the trunk floor. There’s not spare tire, a repairing kit with a compressor, a sealant liquid, auxiliary devices and a limited speed sticker is supplied instead (I guess the sticker is to paste on the rear after using the kit).

Power system and brakes
The vehicle is moved by a syncronous electric motor with permanent magnets that provides 67 hp (49 kW). It supplies a maximum torque of 132 pounds·feet (180 N·m) which remains constant between 0 and 2000 rpm, which is very interesting in acceleration and deceleration on urban traffic. The electric motor spins up to 8500 rpm, when the vehicle reaches a maximum speed of 81 mph (130 km/h).

The wheels are moved trhough a transmission formed by a reduction mechanism and a differential placed next to the electric engine.

This system launches the C-zero from 0 to 60 in 16 seconds and the maker’s energy consumption figure is 216 W·h/mile. The 0 to 60 figures are really slow, however it’s quite fast up to 30 mph. In fact, a regular driver would probably make a shorter time from 0 to 30 with this car than with a 100 hp manual hatchback. Of course, at higher speeds the acceleration is poor.

Batteries
C-zero batteries are placed under the floor of the vehicle. It’s a 16 kW·h, 330 V, lithium-ion pack made by an alliance of Mitsubishi and GS Yuasa. Sigle cells of 3.7 Volts and 50 A·h are employed in the pack.

Groups of 4 units of these cells are built together in series to form a module of 15 V and 50 A·h.

The battery is made up of 22 of those modules connected in series to get the aforementioned 330V and 50 A·h. These data shows a total capacity of 16 kW·h.

In June 2011, the original vehicle manufacturer, Mitsubishi announced it will install Toshiba batteries with SCIB (tm) technology, based on a lithium titanate anode (Li2TiO3 or LTO). This technology allows a charge / discharge current 2.5 times higher than a typical lithium-ion battery and provides 1.7 times the range, with less heating that avoids the need of cooling when the power consumed or supplied is high. It is also more resistant to an internal short circuit and maintains performance levels even in temperatures down to -30 º C. With this technology, the i-MiEV will be able to make a quick charge under CHAdeMO standard up to 80% in 15 minutes, 50% at 10 minutes and 25% in 5 minutes, which approach the Japanese small electric car to the speed of a conventional refueling.

Charging system
Two types of charging systems are present: a slow charge and a fast. To learn more about charging systems you can visit this article.
On the right side is a Mennekes plug, which is used for slow charge. The opening lever is in the lower left area of the dashboard. It’s very likely to find it if you're looking for the way to open the hood, which can be done using another lever, fitted under the glove box in the passenger seat.

The slow charge process can be made in home, using the transformer supplied with the vehicle, or in refueling stations under the IEC 62196 standard using a connection wire that is also provided with the vehicle. This system allows carrying out a full charge in a period of time that depends on the voltage of the outlet. In an European home plug capable of providing 230 V and 15 A, a maximum power of 3.5 kW is provided and the full charge from empty is completed in about 6 hours. Same happens in slow charging posts of the Mobega plan. In a 120 V American plug, the amount of time would double the previous figure. Obviously, this time is reduced if the battery holds some charge.

The left side connector is TEPCO format, which follows the standard CHAdeMO, a fast charging method that can provide high power. A handle on the floor on the left of the driver's seat, which is commonly used to open the trunk or the gas lid in other vehicles, is used to open the fast charge lid. This type of charger is a mode 4 and provides about 50 kW of DC power.

Equipment
Equipment level of this unit included front fog lights, which acted as daytime running lights while the regular beams are not used. In this sense, the vehicle also included automatic lights based on luminosity, but no automatic wiper.

The standard equipment includes air conditioning, radio-cd (navigation system is an option), ABS, traction and stability control and alloy wheels.

How much is this?
The price of the Citroen C-Zero is about $36400 (28000 €) excluding taxes and discounts, like the Peugeot Ion. The Mitsubishi i-MiEV is about $1300 (1000 €) more expensive.

Driving Impressions
Driving this vehicle has many surprises. First one is that the car moves dynamically and the feeling at high speeds even approaches B segment models (Citröen C3, Ford Fiesta, Peugeot 207, Toyota Yaris, Renault Clio ...), although with less stability and a much more notorious feeling of road irregularities due to a kind of hard suspension and a short wheelbase. This is a surprising behavior after checking the agility in city traffic and a decent performance on mountain roads. In general, a higher driving position than in other models of its size, a considerable weight for its size (2634 pounds compared to 1985 pounds of a c1), a low center of gravity due to the situation of the battery pack and the positive point of being rear-wheel driven make this C-Zero an agile city car and a valid option elsewhere. The small turning radius makes it very manageable and there's some entertaining but not dangerous fun in being rear-wheel drive. The smoothness and the overall feeling make it an enjoyable car to drive. In this sense the only drawback is the abovementioned suspension, which transmits many irregularities inside.
If the speed is increased it remind us that we have a couple of oreo sized front wheels. Facing a turn a bit hard creates a notorious understeer, and it is interesting to note that "a bit hard" may be the same speed at which any compact car walks around the curve while the occupants observe the landscape. Inside a C-zero in the same situation a person with heart problems may give some surprise. Luckily, the car informs that it's not comfortable with the situation and traction and stability controls are truly effective. Compared to other vehicles, shows a greater difference between the behavior on wet and dry conditions. Understeer claim a greater role, if possible, with wet pavement. In this situation, the option to turn off the traction and stability controls with a button on the lower left area of the dashboard can be simultaneously the best and the worst idea you’ve ever had: you can have great fun discovering that, in addition to oversteering and understeering, the car can also switch between the two of them, but it feels like life expectancy is greatly reduced.

Returning to the rational use of the car for which it is designed, its driving is smooth, with a direct steering and a nice feeling. The accelerator and brake simulate a conventional automatic, crawling the car if D is selected and using the brake to module progress in maneuvers at very low speed. As in any electric vehicle or hybrid, retention is emulated by the electric motor, which generates electricity absorbing torque when the accelerator is lifted. This retention and the generated energy are higher when the brake is applied gently. According to the parameters set by the manufacturer, the braking torque can be larger or smaller. For example, Toyota hybrids have a low brake torque and you need to use the brakes more times. In the case of C-zero, holding torque is quite high and the decceleration is even greater than in a conventional vehicle with a low gear engaged. This means that you can drive with some agility along a mountain road without touching the brake. I do not think there is a solution that is absolutely better or worse. Perhaps the C-Zero is more comfortable to use once the user becomes accustomed to its operation, because the number of times you need to change the foot between accelerator and brake is reduced. Toyota, on the other hand, is more like a conventional hydraulic automatic gearbox, so the need to press the brake even on gentle slopes is very common. The vehicle brake lights remain off until the pedal is depressed, increasing the risk of rear-end collisions in vehicles like the C-Zero, in which the retention created when lifting the throttle can be more than the expected by the driver following us. Any of these systems requires a period of adaptation, although I am more comfortable with the one from Toyota. I consider it has been a mistake to remove the two extra modes in the shifter of the Mitsubishi i-MiEV, that have to do with this retention torque when lifting the throttle.

The C mode reduces the holding torque and allows to move forward without losing speed. It could be interesting when dealing with hypermiling techniques, which avoid regeneration because it involves losses, so to reduce the average energy consumption it should be used only when we want to slow down. In mode B the holding torque is increased, for example, to go down a mountain pass without needing to press the brake continuously. This B mode has nothing to do with another B mode present in Toyota hybrids, which also provides a higher retention increasing slightly the regeneration and forcing the engine to pump air into the cylinders (by the combined torque of MG1 and MG2) to use engine brake, as in a conventional car. In the case of the Mitsubishi all that energy in B mode is regenerated into the batteries while in the Toyota a very important part of it is thrown away as mechanical losses, so that it is only interesting to avoid overloading the friction brakes if a long downhill is faced with a full charged hybrid battery. In any case, the absence of these two modes in PSA models takes away some interesting possibilities.

Another curious detail that requires a period of braking up is a slight delay from pressing the accelerator to moving the car when starting from full stop, probably around 0.5 to 1 seconds. This means that, sometimes, the driver thinks the acceleration is not enough and increases the pressure on the pedal, creating a rough acceleration. But it's something that you just get used to, so these situations can be avoided.
These are two videos with instrument cluster information:

Starting and computer information

Power indicator while driving

Measurements
The measurements section is divided into 2 parts: the first one is related to speed, height and power consumption and the second one has to do with the energy and the cost of the charging process.

During one day I have made measurements over a distance of about 100 miles (160 km) to assess the overall performance of the vehicle. The eight first sections cover a distance of 65 miles (104 km) without intermediate charging. Battery consumption is very sensitive to differences in altitude and speed, with very intense discharging rates as a result of high power demands when we want to maintain a reasonable speed on long uphills. This is a notorious result of comparing sections 1 and 3. It is important to note that the percentage of battery charge is related to the number of stripes on the dashboard indicator, from a total of 16. Once the last stripe is gone, there is a safety margin, which has been used in part for the section 7.

After section 7 a partial domestic charge is carried out, ending with a 30% of charge. The section 8 is the way to Vigo airport charging station. After recharging, the battery is near 100%.

The section 9 is mostly highway and the highest speeds are reached. Although the route is mainly downhill, battery consumption is high due to the extra power use at high speed.

The rest of the stages, from 10 to 13, are a mix of urban and inter-city routes. The battery charge sensitivity to facing slopes is shown again, particularly in the section 12.

One interesting subject is: How much is the energy cost of an electric car versus a conventional car?. Assuming an 80% charging efficiency, 20 kW · h of electricity would be used in a full charge. The current price in Spain is 0.195 $/kW·h (0.15 €/kW·h) for a normal plan or 0.104 $/kW·h (0.08 €/kW·h) in the night period if you have a plan with different prices for night and day use. In the first case would be about 3.9 $ (3 €) and 2.08 $ (1.6 €) in the second one. With this cost the car should be able to travel about 60 miles (100 km), representing an average cost of 0.062 $/mile (0.03 €/km) or 0.033 $/mile (0.016 €/km), depending on the electric plan. An efficient vehicle with internal combustion engine like a Toyota Prius or a VW Golf 1.6 TDI 105HP has an current energy cost in Spain of 0.145 $/mile (0.07 €/km). Therefore, depending on specific conditions, the cost per km is between half and a quarter of a conventional vehicle.
To check the real energy consumption, a measurement has been carried out during a one way trip from Ourense to Redondela. The origin is 420 feet (130 meters) higher than the end point, so the energy consumption will be slightly lower than in a round trip. The vehicle started fully charged after a slow charge at Ourense and reached the destination at Redondela with 3 stripes (3 of 16, approximately 18%). The home charger was connected to a wall outlet through a power meter. The following data were obtained:

Distance traveled: 63 miles (102 km)
Maximum power consumption during charge: 3095 W
Energy consumption during the charge: 12.75 kW·h

The average consumption can be expressed as:

12.5 kW·h/100km. (lower than reported by the manufacturer)
20.1 kW·h/100mile
169 mpg-e
1.4 L_equivalent/100km

With the kW·h consumed at 0.15 €/kW·h, the total cost is 1.91 €, with a ratio of 1.87 € / 100km, so 0.187 € / km (significantly less than previously estimated, probably due to an economical driving, the altitude difference and a charging performance higher than estimated).
Anyway, for a conclusive data would be necessary to assess the cost of maintenance. This is significantly higher in conventional cars, but can be severely influenced in electric vehicles by the life of the batteries. If at 100,000 miles € 15,000 need to be spent on batteries, the cost per km is increased by 0.10 € / km, resulting in a total (fuel + maintenance) comparable to that of a conventional car. In this sense, the use of leased batteries that Renault offers for its electric vehicles is a good way to control these costs and avoid surprises in this first generation of vehicles.

Conclusions
The Citroën C-Zero is shown as a perfectly valid option as everyday vehicle that meets the needs of a large percentage of the population. It is reasonably light, has a reasonable interior space and driving is very simple. It can be used at all times with the amenities of any combustion vehicle to maximum legal speed on highways, provided that the owner is willing to pay the cost in terms of reduced autonomy. It is a vehicle oriented to urban traffic and its dimensions and approach are consistent with the philosophy of a vehicle that respects the environment.

The main downside is the price, which could be detailed as the price of a Citroën C1 + batteries. However, we do not have anything like the convenience, comfort, quality of materials or performance of a conventional vehicle in the vicinity of € 30,000.

Someone may think that the low energy cost can offset its higher price. Compared to a Citroen C1 in the vicinity of € 10,000, € 20,000 must be amortized. We can say that we will spend about 13.5 kW·h/100 km, while the approved comsumption for a 1.0 12v is 4.3 L/100km. At today's Spain prices (and using reduced hourly rate to charge electricity) this represents a cost of 0.95 €/100km for the electric vehicle and 6.45 €/100 km for the conventional. It seems much advantage for electric, but mean more than 360,000 km traveled to compensate the price difference. In my opinion is too much to trust the battery life, and even the car itself.
But the price is not, in my opinion, the only negative point. The quality of many materials, the seats and the lack of a more high tech interior are other areas for improvement. Chelsea Sexton, in the podcast Whatdrivesus defined his twin, the i-MiEV, as an analog car, something that I agree completely.
With its pros and cons is a coherent proposal for the growing electric market. Some time will go by before these cars become more widespread and, meanwhile, battery technology needs to be improved and manufacturing costs should be reduced. But, undoubtedly, is a good proposal, interesting and coherent. It may be an option to consider for environment-conscious drivers, especially in urban areas.

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Thursday, December 6, 2012

Citroën C-zero

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