Tesla ran a computer simulation ranking its four Model S variants (the numbers indicate the capacity of the battery; the D stands for "dual motor," which on some models assigns a dedicated motor to each axle) under ideal driving conditions and found that traveling at conservative speeds, the Model S could achieve a range of more than 400 miles.
In a blog post, Tesla points out that a Model S's range isn't just affected by its battery, but also by the size and type of its tires. Tesla's 21-inch tires are a good choice for folks who want the best performance, but it comes at a 3 percent cost to range, the company said.
There are "many customer vehicle configuration choices, both before and after purchase, that can affect range as much as or more than the vehicle platform choice itself," Tesla wrote.
Most actual drivers aren't going to get anywhere near the kind of fuel economy described in the far left part of the chart above; you're just not going to be driving at 40 miles an hour on flat highways all the time. In EPA tests, the company came away with results more in the 200- to 300-mile range.
Still, the thought of driving from Washington, D.C. to Boston without stopping to charge up once is a tantalizing idea. You can test out Tesla's assumptions for yourself with a range calculator they've developed.