EV1 Handling Impressions

Having driven EV1s for more than a year, I may be able to make some useful observations. First the EV1 is an outstanding engineering achievement. Its bonded and spot welded aluminum chassis weighs 290 lbs and the car without batteries weighs about 1800 lbs. It is extremely efficient. EV1 can travel about 75 miles on the energy equivalent of 1 gallon of gasoline. It cost 1-2 billion dollars to develop which puts the cost per car around $1-2 million. Note that EV1's very stiff bonded Aluminum chassis predates Elise' use of adhesives by a few years. EV1 uses mostly stampings with some welds and rivets in contrast to Elise mostly extrusions with some screws and rivets.

Many steps were taken to improve efficiency, from Magnesium and reinforced plastic interior parts, to a 0.19 drag coefficient, to special very low rolling resistance, 50 PSI, 175/65-14 Michelin tires. With low drag and 100% torque from 0-7000 rpm the car comes up to speed briskly at under 8 seconds to 60 mph. As a sign of efficiency, on a highway downgrade with regenerative braking and throttle off, the car accelerated beyond 75 mph due to low drag. Starting from near top speed the no-power coasting speed increased rather than diminishing.

It is the skinny tires in addition to 1100 to 1300 lbs of Nickel Metal Hydride or Lead-acid batteries that probably affect the handling the most. EV1 handling is not tuned as a sports car, but considering the tire size and weight, it handles competently. Lane change transient response is quick and predictable, but like all lateral motion it is accompanied by a lot of well-damped roll. It rolls quite a bit in steady state turns also, but takes a fairly predictable and stable set pretty quickly. The large mass of the battery pack and its effect through roll are very noticeable, perhaps more so since the rest of the car is light and rigid.

The tall, skinny, hard tires feel unusual. EV1 has about twice the static vertical load of Elise on a similar sized contact patch. The low-energy-loss sidewalls and tread don't flex much so they seem pretty willing to generate slip angles quickly. Being skinny they don't seem to have a lot of grip, but the large load seems to compensate somewhat. So the car seems to generate slip angles pretty quickly but also holds moderate ones pretty well due to all the load. Again it's no sports car, but given the design constraints the car handles very well, certainly much better than GM sedans I've driven lately.

EV1 has upper and lower A-arm front and beam rear suspensions. The front drive shafts pass straight through a fork at the bottom of a tall uprights. The rear has a Panhard rod, and the front has an anti-roll bar. Major suspension components are Aluminum.

An article about EV1 by Daniel Pund gives due credit for much of the results:

The car must handle and have a ride quality equal to or better than that of a traditional car. Constant tuning of the suspension, both on test mules and in computer simulations, brought the handling to a level of sophistication and competence unexpected at the start of the program. Much credit goes to Clive Roberts, a British engineer originally on contract from England's Lotus Engineering, who became lead development engineer in 1991 and oversaw the development, and is now with GMATV. [Advanced Technology Vehicles is GM's skunkworks.]

The EV1 actually had a couple of things going for it in the handling department. The placement of the battery pack in the structure's central tunnel provides near-perfect 50/50 weight distribution. And the stiffness of the structure as a whole allowed for more latitude in tuning the suspension.

All this ignores the controller, battery technology, power management, etc., which are very impressive. More info at:
Jeff C.