Saturday, April 13, 2013

BMW Car Control Clinic in an ActiveE

Last weekend I had the opportunity to take my BMW ActiveE to a Car Control Clinic run by the BMW Car Club of America, Golden Gate Chapter. I know the car can handle pretty well, so I was very much looking forward to driving it closer to its limit. However, since the clinic took place over 30 miles from my house, I wasn't sure how much battery charge I would use first getting there and then participating in a full-day clinic of hard driving. Luckily, there are hundreds of free EV charging stations along the route between my house and Candlestick Park where the event took place, so I decided to head up early and get a top up charge at a free parking garage in South San Francisco. After the top-up I arrived with over a 90% charge and throughout the day used less than half my charge. If I participate in a followup performance driving clinic I'll feel more confident in skipping the morning top-up.

As for the event itself we rotated between three stations participating in:

  • A skid pad to test under and oversteer and the limits of adhesion in the ActiveE.
  • A high-speed braking and accident avoidance exercise to get experience with full anti-lock braking stops
  • A minor autocross cone course.

I've done all of these activities before in other BMW cars at the BMW Performance Driving Center in South Carolina, so I was most interested in those exercises that highlighted performance of the electric car. The most surprising thing initially was how well this relatively heavy car comes to a complete stop at speed with full anti-lock braking. Perhaps less surprising is the fact that with instant torque, 50/50 weight distribution, and solid handling the ActiveE is great on autocross courses.

Don Louv reports in the April 2013 issue of Roundel magazine that the ActiveE doesn't let you turn traction-control all the way off so he's been unable to get it drifting sideways. On the skid pad, I had the same feeling after turning the stability control off that it was still fighting my oversteer with a bit of understeer. I could certainly get it sliding for short periods of time but it was still fighting me. The skid pad was dry however, and I didn't adjust my tire pressures, so I'd like another go at it in wet conditions to keep the car sideways longer.

Sunday, January 27, 2013

ActiveE Torque Measurements

One of the most amazing things about driving an electric car is the instant torque. The ActiveE is fun to drive, but it is sometimes hard to compare against internal combustion engine cars. When my local chapter of the BMW Car Club of America recently held a Dyno Day, I was eager to put the ActiveE to an objective performance test. Dietsch Werks at Club Auto Sport just installed an in-ground AWD Chassis Dyno built by SuperFlow Technologies Group to measure torque and horsepower output. There were more than a dozen cars at the event, and of course someone scheduled the whisper-quiet electric car behind an M5 with an amazing exhaust note. Luckily, nobody was disappointed with the muted electric vehicle, especially after the torque numbers started showing up on the screen.

The ActiveE put up by far the largest torque numbers of the day, ahead of an X5M, M5, and plenty of other Porsche 911s and BMWs. We did runs with and without Eco Pro mode and the numbers came up to 490 pound feet of torque without eco pro mode, and over 460 pound feet of torque with it engaged. As expected for an EV, the torque curve shows maximum torque shortly after rest, however, the number is significantly higher than expected. The BMW ActiveE page notes that the electric motor puts out just 184 pound feet of torque, so I'm not sure what to make of the large discrepancy.

After the run, nearly every warning light on the car's dashboard was illuminated. As is often the case with the ActiveE, however, just giving it the old Microsoft Windows treatment of turning it off and back on again cleared everything.