ALSO SEE: Updated 2016 Tesla Model S 90D now rated at 303 miles highway range (April 2016) It appears the new versions actually use a 75-kwh battery pack that's software-limited to provide only the range of a 60-kwh pack. "Model S 60 and 60D owners may later choose to upgrade their vehicles to a 75kWh battery with a software update," Tesla said today, "should they want to add to their car's battery capacity in the future." That's an echo of the company's original approach to the handful of 40-kwh Model Ses it sold in the car's earliest days. Tesla originally offered capacities of 40, 60, and 85 kwh for the 2012 Model S lineup. So few buyers opted for the 40-kwh version, however, that the few who took delivery before Tesla withdrew it from the lineup received a 60-kwh car with software limiting the range to that of a 40-kwh battery. As battery technology has improved and the energy densities of lithium-ion cells have increased, Tesla has made several changes to battery specs over the life of the Model S thus far. The Model X electric SUV was announced with capacities of 70 and 90 kwh, but by the time it reached production, the 70-kwh pack had been supplanted by a 75-kwh battery.