At 50 mph, the Mitsubishi i-Miev can go 70 miles on a charge, the Nissan Leaf 97 miles, and the Model S 300 miles.
Compare this to what those cars can do at a typical 70 mph speed: 260 miles range for the Model S, 68 miles for the Leaf, and 40 miles for the I-Miev. That's about a 15% range gain for the Model S, a 63% range gain for the Leaf, and a whopping 75% range difference for the I-Miev. The Tesla Model S's being a heavy and aerodynamic car factors into its inefficient low speed range and more efficient, relative to that, high-speed range.
By the time back-to-school ads for Staples are running in your local newspaper, Tesla will be preparing the launch of its highly anticipated Model X fully battery electric SUV (technically, it's a CUV, or crossover utility vehicle). This full-size model, which will offer performance rivaling that of Porsche's respected Cayenne, will feature unique Falcon Wing doors (the term "gull wing" apparently wasn't disruptive enough) and seating for seven adults---plus ample room for luggage, golf clubs, and antique furniture.