Because zero to 60 in 3.2 seconds and a top speed of 130 miles per hour are just not enough,
The Palo Alto car company said in an asterisk attached to its online Model S specifications sheet that the new performance levels can be achieved with a free software upgrade.
The upgrade applies to Tesla's more powerful Model S 85D, which has a more powerful battery and longer range than the base Model S and produces roughly the same 380 horsepower from a dual motor that distributes power to both front and rear wheels.
But it also applies to the P85D, which is a Model S outfitted with the larger battery and dual motor paired with a performance package that produces 691 horsepower -- 221 horsepower at the front wheels, 470 horsepower at the rear.
Heretofore, the 85D and P85D had been electronically limited to 130 mph.
The 85D starts at $85,570 and the P85D at $106,570, before rebates -- somewhat above the $74,570 MSRP for the entry-level Model S.
The online statement reads, in part:
"The P85D top speed is currently electronically limited to 130 mph. In the coming months, we will be able to upgrade the car free of charge to enable a 155 mph top speed. This free update will be available for the lifetime of the car (not limited to the first owner). Additionally, an over-the-air firmware upgrade to the power electronics will improve P85D performance at high speed above what anyone outside Tesla has experienced to date."
That last bit is apparently a reference to performance issues that some testers had with the P85D's torque.
An independent dynamometer test, reported this week on the auto blog Drag Times, put the dual-motor P85D's torque level at an astonishing 864 pound-feet.
But Drag Times also found the vehicle had difficulty maintaining that torque level. The Tesla phrasing about improving performance at high speed "above what anyone outside Tesla has experienced" seems to address that.
The "over-the-air firmware upgrade" could mean an improved zero to 60 score, too.