I recently saw a blog posting http://jackrickard.blogspot.com/2010/07/more-regenerative-braking-results-it.html where the writer said that he'd tested regen on a couple of EVs, and according to his tests more energy was used when regen was on. That didn't seem right to me. I assumed he was driving differently with regen, trying to use it often as if it was a magic way to add range. Of course it can't add to your theoretical range; it can only add to your observed range by keeping you closer to your theoretical range. It only helps if you regen instead of wasting energy by braking. Regenerating when you don't need to slow down is a waste, so not braking at all is best if you can swing it. I tried my own simple test to make sure that regen really helps on our Roadsters. This was a short drive, and I only did it twice, so this is not authoritative, but I feel better that the results were as expected. I took two trips; in the first I drove normally (using regen on the accelerator whenever I wanted to slow down); in the second I tried to drive exactly the same, except for when I started to slow down--then I would pop it into Neutral and use the brake pedal. I took exactly the same path each time; traffic was not identical but it seemed there were a roughly equal number of slowdowns on each trip; when possible I used cruise control to keep at the speed limit; I tried to accelerate at 25kw each time. I drove in a triangle: 1. On the 1.65 mile 35mph 300' uphill leg, I used 747wh with regen, and 824 without. That's 10% more energy without regen. I had to stop about 5 times, so that's where regen was useful. 2. On the 2.05 mile 60mph 300' downhill leg, I used 183wh with regen, and 376 without. That's 105% more energy without regen. Note that much of this downhill was at freeway speed, so I was still using energy (no regen) despite going downhill. It wasn't until the stoplight at the bottom that I used regen. That was the only stop on this leg (there was another light, but I hit it green both times). 3. On the 1.8 mile 35mph flat leg, I used 400wh with regen, and 470 without. That's 17.5% more energy without regen. There were 3 stops and a couple of slowdowns on this portion. For the overall trip, I used 25% more energy when not using regen. I guess a better way to say it is that I didn't reclaim 20% wasted brake energy when I didn't regen. The overall difference after all the ups-and-downs is, no surprise, roughly similar to the difference when driving on the flat and making occassional stops. Going downhill obviously gets you the biggest gains. Going uphill gets you the least; even if you make stops, gravity is doing some of the work rather than regen. Everything is pretty much as I expected it to be, so I feel better now.