One car, two ranges: Tesla claims 300-mile Model S will be EPA-rated at 265

Tesla Model S corneringTesla Motors says the top-spec version of its Model S sedan will have a 300-mile range. However, the company also says that the EPA will probably rate the Model S at 265 miles. How can one car have two quoted ranges? According to Tesla’s official blog, it all comes down to how the Model S is tested.

The testing procedure can dramatically affect a car’s range. The Model S has actually gone over 300 miles (320, to be precise) between charging in testing, but only with the old EPA two-cycle fuel economy method. Tesla is saying that under the current, five-cycle, testing regimen, the Model S will only go 265 miles.

The five-cycle test is more comprehensive than the two-cycle, which explains the two different ranges. Whereas the old test only involved city and highway driving, the five-cycle includes a cold start test, an aggressive acceleration test, and a few miles driven with the air conditioning on. All tests are conducted on a dynamometer for consistency.

The five-cycle procedure also weighs scoring differently. The two-cycle gave city driving a 55-percent weighting; highway was 45. The five cycle weighs city driving at 43 percent and highway at 57 percent.

Tesla based the Model S’ 300-mile rating on the old two-cycle test, and expects that number to drop to 265 miles in the five-cycle test. Looking on the bright side, Tesla CEO Elon Musk and CTO JB Straubel noted that the 265-mile range is an improvement over the Roadster’s 245 (that car was tested under the two-cycle regimen).

The projected five-cycle range of 265 miles is still pretty impressive; a Nissan Leaf is only rated for 73 miles. However, Tesla may need to attach some asterisks to its Model S badges. Real world conditions are very different from the controlled setting of a laboratory, hence the “your mileage may vary” fine print in most car ads. The Model S may have superior range, but if drivers’ numbers don’t match the ones quoted by Tesla, the company may still have a lot of explaining to do.

Most cars have trim levels based on equipment, but the Model S comes in three versions with different ranges: a base model that can go 160 miles between charges, an intermediate 230-mile model, and the top 300-mile version. The different ranges are due to the size of each model’s battery pack. The 300-mile Model S has an 85 kWh battery pack. Tesla did not release estimates for the 160-mile and 230-mile model’s five-cycle ranges, but they will likely drop as well.

Buyers will find out just how far the Model S will go next month, when the first cars reach dealers. The new sedan will cost between $57,400 and $87,400, depending on the trim level and options selected. Like other electric vehicles, the Model S will be eligible for state and federal tax credits.

Hopefully, buyers will not quibble over 35 miles. Tesla needs the Model S to sell well; the company lost $89.9 million in the first quarter of 2012, and will start repaying $465 million in government loans this December.