Winter chills limit range of the Tesla Model S electric car

We've been enjoying the Tesla Model S as it goes through its break-in period, leading into formal testing. During this time, I've been keen to find out its real-world range, and recently confirmed that driving this electric car—like any other—can bring some range anxiety. Although winter highway driving may present a worst-case scenario, our Tesla actually delivered the range it projected.

It was a chilly 45° F when I pointed our fully charged Model S homeward for my informal experiment, a distance of 75 miles. With 240 miles on the car's range indicator, I figured there would be more than ample juice to cover the distance, plus some nighttime errands, the morning drop-off at school, and then my 75-mile return trip to the track. The Model S has an additional range predictor called "projected range" that estimated 188 miles remain. This secondary display is part of the energy graph, a function you can choose to view on the large iPad-like screen. The projected range takes into account ambient temperature and driving style, and it provides a more accurate estimate than the default display. Based on that estimate, too, the range appeared to be sufficient.

Although the car predicted its range fairly accurately, I barely made it back to the office the next day, running the last three miles on an indicated zero charge. Yes, I was a bit stressed, but the car did what it said it would. The entire trip totaled 176 miles. So, how did I run the battery all the way to empty?

Our S has the larger 85-kWh battery, the one Tesla claims is good for 300 miles in optimum conditions. The EPA pegs the range at 265 miles. In our experience with other EVs we've tested, we've come mighty close to the EPA's estimate on range. In general, we heed Tesla's advice against charging for "max range" due to the adverse effect on battery life, as any other owner would, and charge in "standard" mode.

According to Tesla, the rated range indicator (front and center in the instrument panel) is based on the EPA's "rated" 265 mile range. When I got home with 80 miles on the trip odometer, I noticed that 100 miles got slashed from my "rated" range, showing 140 miles left. (See our alternative fuel guide and fuel economy guide.)

Anyhow, after a seven-hour overnight park (unplugged) and temperatures dropping below freezing, the "rated" range dropped to 65 miles. (Because we're tracking energy poured into the Tesla at our track, I resisted the temptation to top off at home, like a typical owner would.) The "projected" range was even scarier at 15 miles left after cold soaking at 30° F through the night.

But by now I've gained enough familiarity with our Tesla to assume the car would readjust once I started driving and things warmed up. (Owners would likely pre-condition the car before leaving, using household current to raise the battery temperature and heat the cabin.) Indeed, 30 miles into my trip, the car predicted 55 miles of range. Occasionally the "rated" and "projected" agreed. I considered stopping in Milford, CT, for a quick "supercharge" as I had a few days earlier, but changed my mind in the spirit of my experiment. I knew the distance to my office was 55 miles at that point, so I decided to risk taking one for the team to determine the Model S real-world range when it's cold outside and you drive the car as you would any other car, electric or not. Call me a gambler, but I kept cruising and crossed my fingers.