Several
years ago, GM has displayed an electric show car named "Impact" in
Detroit
motor show. In 1997, Impact eventually went into production, but this
time
called "GM EV1". Very interesting, this innovative car is the first
General
Motors car sold under the brand "GM", although GM was found as early as
1930's.
EV1 is the first mass production electric car in the world. Electric cars have many technical difficulties, such as the range of running, weight of battery, battery life, performance, charging time and price. Among which, the battery is still the most critical and unsolved problem. The most common lead acid battery is cheap, but it stores little electricity so that the range of running is very limited. Moreover, it takes probably 10 hrs to charge, so you have better to charge your electric car at night. On the contrary, NiMH (Nickel Metal Hybrid) battery is faster to charge and store more energy, but it is so costly that make mass production nonsense. No matter which battery, all of them have short life and they are very heavy ( the battery of EV1 weight as much as 500kg ! ), as a result, performance is considerably deteriorated. The philosophy of EV1 is sensible : unlike other competitors, EV1 is designed to be an elegant coupe. If it were an ordinary small sedan, it would be impossible to compete with those more economical and practical petrol cars. A coupe is unnecessary to be practical, nor economical. And its price is less sensitive. Moreover, sophisticated looks, show-car-like interior design and the name "Electric car" help it to grab the heart of some niche buyers. In technology, GM has no innovation on the battery. Instead, it optimises the rest of the car to improve performance. For example, its drag coefficient of 0.19 is a world record, breaking the previous record set by Opel Calibra's 0.26 by a large margin, thanks to the narrower tyres, no-vent nose and carefully revision in wind tunnel. Its electric motor is also very powerful. It is a three phase induction AC motor. The dc supply from the battery should be converted to ac then 3 phase ac before input into the motor, very complicated, but it really allows greater power - 137hp and 110lbft maximum, Wow, what an electric car ! From this engine, we have learned that electric motors have very different power and torque curves - in EV1, maximum torque appears right up from the start to 7000rpm without variation, then from 7000 to 13000rpm the maximum power occurs. Since the torque is so constant, EV1 need no gearbox. Reverse can be done by reversing any 2 inputs to the motor. Apart from the powerful engine, GM also want to improve the performance further by reducing weight. Therefore, aluminium space frames chassis is adopted, which is enclosed with a mixture of plastic and glass fiber body panels. Such measures reduce the weight to "only" 1360kg, for a small 2 seats coupe ! Thanks to the half tone of batteries. OK, the batteries are heavy, but at least they can keep the center of gravity low, especially when they are put under the seats and inside the central tunnel. We have talk so much about spec and so on, so, how does EV1 behave on the real road ? The first impression is : the engine is turbine-smooth, and extremely quiet. Like a washing machine. It rides well, handles average because of the weight. Performance is better than many petrol cars : 0-60mph in 7.9sec according to R&T, or 8.4sec by C&D. Top speed, though, is electronically limited to 80mph. Although fast,
you cannot
expect it to be a fire ball coupe. Remember, it is still an electric
car,
the car which provides the vision of the future, a car which is built
to
satisfy the US government and California's zero emission law effective
on early next century. Consider the charging time, the 60 to 90 miles
range
and the leasing cost ( EV1 is not for sold. ), we still think the age
of
electric car has yet to come - at least until a revolutionary battery
is
invented. |
The above report was last updated in 1998. All Rights Reserved. |
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