55 miles. http://www.google.com/search?q=top+gear+tesla+roadster+55
The Roadster has also been informally tested by a Hacker News reader: http://news.ycombinator.com/item?id=318154
it will be the laughing stock of any track day.
First off, as Wil pointed out, it doesn't like staying at 100mph+ for very long. That naturally makes it not a track friendly car. It will get passed up easily on the straightaways at some tracks (ex you can hit 140+ on the back straight at Road Atlanta). And the brakes will get roasted and it will run out of battery after just a few sessions. ... In summary the Tesla is not a car guy's car, it's a SV show-off car.