Mitsubishi iMiEV: firstdrive

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The Mitsubishi i-MiEV ('eye-meev') is a rather distinctive Electric Vehicle (EV) based on the standard Mitsubishi 'i' car from Japan (a few ICE models were also sold in the UK in 2007) It is a 'conversion' in as much as it was re-engineered as an EV from a conventional vehicle, but these cars are now rolling off the production line in Japan as EVs. It will be marketed in the UK & Europe by Mitsubishi and also by Peugeot and Citroën (as the iOn and C-Zero respectively) with mostly cosmetic and interior specification differences.

The i-MiEV (Mitsubishi innovative Electric Vehicle) is a fairly tall, narrow car, but with a surprising amount of front and rear space for 4 adults, easily accommodating someone over 6'2" in the rear: Currently, there are 50 vehicles on the road in the UK: an early batch of 25 pre-production vehicles in distinctive two-tone, red and white livery and another batch of 25 more conservative all-silver vehicles: these are actually Japanese-market production vehicles - the only giveaway that they are not European models being the Japanese-sized number plates. These vehicles are mostly supplied through government funded trial projects to different end users for evaluation.

Mitsubishi i-MiEV, at St Michael's Mount, Cornwall © ecodrive
The i-MiEV carries its lithium battery, a more 'conventional' battery than that in the Nissan LEAF, made up from modules assembled into a battery pack, underneath the vehicle in a tray leaving the interior space untouched.

The electric motor and drive electronics are under the boot floor, driving the rear wheels. The rarity of rear wheel drive on an undeniably city car (few other examples such as the Smart car use this layout) liberates the steering geometry on the front wheels to give a phenomenal steering lock which must rival a London black cab for its ability to make a U-turn in the street!

The multi-function keyfob which allows you to set various alarm options, fold in the electric mirrors or unlock the doors automatically as you approach, merely needs to be in the car to allow you to get underway: a chunky plastic 'key' is where you would expect to insert a key into the steering column... but if that technology fails, you can unclip the plastic imposter and flip out the conventional key from the fob to do it the old-fashioned way.

The i-MiEV has a conventional, automatic-style, selector lever with Park, Reverse, Neutral, Drive, Eco and Brake positions. The Drive position gives full acceleration whilst Eco 're-maps' the accelerator pedal, meaning that you have to press it harder/further to achieve the same effect and removing the 'top end' of the range - limiting the available power, but still giving a very useful amount, whilst encouraging more efficient driving and stretching the 'range'. The Brake mode introduces a stronger regenerative braking (or 'regen') function than the minimal amount in Drive or Eco when releasing the accelerator pedal: not as strong and useful as expected, by comparison to other EVs. Strangely, the Brake mode gives full acceleration capability - the performance really should be the same as in Eco mode, especially as the car responds instantly to the throttle position when moving the lever to another selection, so when 'downshifting' to B from Eco (in anticipation of a descent) still with some 'throttle' applied, there is a little burst of unexpected acceleration until you compensate your foot position.

This is largely a moot point now, because we have since been informed that the UK/European-specification vehicles will be different anyway: there will only be two modes: 'Drive' and one other, expected to be the combination of Eco and Brake: limited power but stronger regen than previously. The lack of (enough) regen, especially in hilly terrain (or heavy traffic) means that too much of your braking is using the normal, friction brakes which simply wastes energy.

Mitsubishi i-MiEV © ecodrive
Driving the i-MiEV is pleasurable if unremarkable: excellent all-round visibility and a slightly higher than normal driving position suit urban life and ease parking, though its tall body and skinny (but Low Rolling Resistance) tyres can make it a little skittish in cornering, especially on poor surfaces. Whilst the 48kW (64hp) motor power figure may not sound like much (it's similar to the peak output of a 1.2 petrol engine) the near continuous torque of 180Nm is more akin to the peak of a 1.6 TDi. Its weight of around 1,060kg means that the torque gives it surprisingly spritely acceleration which is more than adequate to cope with city and town driving. The published top speed of 80mph should not be taken as a target, but more a reassurance that you can hit and maintain 70mph if your normal route to work/school/shops/home includes a few miles of motorway or dual-carriageway.

The range on the i-MiEV is lower than we would have liked. Despite the battery being lithium-based, Mitsubishi have only installed 16 kiloWatt-hours (kWh) of storage. Based on our extensive experience with older generation cars (Peugeot 106) with the same kerb weight and a 50 mile range from 12 kWh, we expected little more than the proportionate one-third increase, which would suggest about 70 miles... we weren't far off in our estimation. Mitsubishi claim an 80 mile range (and Peugeot claim an absurdly high 93 mile range for the same rebadged vehicle) The lower figure could be attainable in a very flat terrain with little traffic and keeping to a modest speed, such as we have observed in Denmark. In the UK, in typical use, we suggest that a 65 mile usable range is a more accurate guide.

What coud be of concern is that, if a new vehicle will just meet your needs, either for a commute or as a more general purpose vehicle, factor in a rough guide of a 2% decrease in range year-on-year as the lithium-ion battery capacity diminishes and that will be dipping under 60 miles after 5 or 6 years of average mileage. Our own empirical observations highlight that heavy traffic, heavy rain (and therefore drag-inducing surface water) and challenging terrain will rob you of a few miles over the entire range; an agressive driving style or continuous use of the electrically driven heating or cooling considerably more.

Hot and cold

The use of air-con decimates range (by about 10%) particularly since it can easily be accidentally switched on (as we did) by turning the air flow control knob fully anticlockwise. I hope that the UK production model eliminates this potential problem and requires a 'definite' action to engage. As with ICE cars, but to a greater degree, if you can park out of direct summer sunshine and 'vent' the car before driving, you will be more comfortable AND save valuable energy.

Unfortunately (unlike the Nissan LEAF) on the i-MiEV you don't have the option of 'pre-heating' or 'pre-cooling' the interior from mains electricity before setting out, meaning that you will be using some of the valuable battery capacity - especially if your vehicle is spending its nights outside in winter or parked in direct summer sun. There will be optional heated front seats, which we strongly recommend if you will often be driving solo or with only one passenger, e.g. in an early morning commute, since it is far more efficient just to heat YOU than the entire cabin!

It is worth mentioning that the generally accepted industry norm for EV batteries is that they are considered 'end of life' when they are down to 80% of their nominal, published (new) capacity. When their capacity has diminished to this level, it doesn't mean that they are 'dead' and only suitable for recycling, but consideration will/should be given to replacing the battery pack and using the old one in a second life application, such as a backup power supply for a computer server installation which doesn't make such arduous demands of the battery. We wait to see what battery performance parameters are specified by the manufacturers for their warranty, since 80% on this vehicle would equate to, at best, a 56 mile range in our estimation. Despite the 5 year warranty, this limitation on the liability is worth bearing in mind.

Mitsubishi are following the model of selling the battery with the vehicle, rather than leasing the battery (as favoured by Renault and ourselves) not least because of pressure from the fleet industry for calculating Residual Values. An advantage over other models such as the Nissan LEAF is that the long-term maintainability of the battery seems better: any individual failing module or cell (of which there are 88) could be economically replaced even outside of the 5 year / 62,500 mile warranty - not confusing this with the 'natural' ageing from high mileages which will affect all the cells fairly evenly.

The inclusion of the battery with the vehicle raises the price to £23,990 (after the £5,000 UK government consumer incentive grant, available from January 2011) The economics of the 'buy the vehicle, lease the battery' model are much more on a par with a conventional vehicle where the battery lease cost plus a fractional cost for the recharging energy equates (subject to covering a certain minimum mileage) to the fuelling cost on an ICE vehicle. We estimate that, compared to a conventional vehicle costing about £12,000, the i-MiEV can be cost-neutral over its life with mileages above about 11,500 per annum, even outside of Congestion Charging zones. In London, saving £8 per day on the Charge and further savings on parking, the car can pay for itself within a few years.

Charging

i-MiEV 'normal' charging inlet, behind the flap on the driver's side rear corner © ecodrive

The i-MiEV only comes with an 'onboard' (built-in) 3 kiloWatt (3kW) charger which equates to a full charge taking about 6 hours (typically overnight, benefitting from cheaper and environmentally friendlier off-peak tariffs) or, equivalently, repleting about 12 miles' worth of charge per hour of daytime 'topping-up' or 'opportunity charging' whilst the car is sitting idle. The first of two charging inlets on the car is behind a conventional fuel filler flap on the driver's side rear corner, accessed by a release lever on the dashboard.

Mitsubishi (and Peugeot/Citroën) are supplying the cars with a simple 'dumb' charging cable with a conventional 13 Amp plug. We have concerns about this approach as indicated in our publication "Safety Issues concerning Electric Vehicle charging stations using conventional UK socket outlets." To use the full 3kW rate drivers should use a dedicated charging station in a public place or a 'wall box' at home. Vehicles should not be treated as electrical 'appliances' without additional precautions. ecodrive will supply alternative charging cables and charging stations / wall boxes for safer charging.

The i-MiEV, following the Japanese convention and in common with the Nissan LEAF, also features the ability to rapid charge from an off-board DC charger, pushing high current energy directly into the battery through a larger, similar inlet to the 'normal' one on the opposite, passenger side, rear corner. The same connector (and same chargers) can be used on the LEAF and other forthcoming vehicles, despite differences in the specification of the different vehicles (different types of batteries, of different voltages or capacities) since the whole process is controlled by an exchange of information between car and charging station.

At the extreme this will take the car from empty to 80% charge (it has to slow it down then to avoid excessively heating the batteries) in as little as 30 minutes, from the chargers touted for public places in pilot areas. More typically, as a private driver, you would generally use one of these chargers in a convenient location for about 10 minutes, to extend your range by about 30 miles, on the rare day that your travels take you further from home or the combination of your errands and journeys have left you a little nervous about getting back home or to your next destination (with a 'conventional' charging opportunity) It is a pity that there will be no intermediate charging solution between 3kW onboard and an expensive, and thus far rare, 50kW off-board charger.

Verdict

The Mitsubishi i-MiEV (and the rebadged Peugeot/Citroen model) is a great contemporary city EV, comfortably seating 4 adults, with more than adequate performance and simple to drive. The only real criticism it is that the battery is under-sized for all but modest urban uses or a regular commute, giving only an approximate 65-70 mile practical range. This would be mitigated somewhat by an intermediate charging solution beyond the 3kW level.

The Mitsubishi i-MiEV is available to order NOW for delivery from January 2011 in limited numbers, from £23,990 including battery.

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