Tesla Model S Owners Claim P85D Has Less HP Than Promised


Tesla Model S P85D owners are questioning whether their vehicles actually have the advertised 691 horsepower.

One group of Tesla owners sent an open letter to company CEO Elon Musk, challenging the American automaker’s claim that the P85D makes 691 hp.

“The P85D was marketed as making 691 horsepower. It doesn’t. We believe, based on various testing methods and tools including dynamometer testing and testing with professional performance data loggers that the maximum energy output is 415 [kilowatts], which results in a maximum horsepower of 557 before any drivetrain losses on a fully charged battery. Even without factoring in drive train loss, this is almost 20 percent less than the advertised horsepower,” said the letter. “The missing horsepower is quite noticeable at highway passing speeds. For example, from 70-90 mph, the P85D should perform like a car with a power to weight ratio of one HP for every seven pounds. Instead it performs like a car with one HP for every nine pounds. The result of this is that from 70-90 mph the P85D is easily outperformed by an Audi RS7 with a power to weight ratio of only one [horsepower] for every eight pounds.”

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Since then, Tesla chief technical officer JB Straubel has taken to the company’s blog to explain a bit on how electric power is defined in terms of horsepower, saying that it isn’t very intuitive. “Electricity alone can’t generate physical motion the way a horse or a fuel-burning engine does,” Straubel explained in the post. “An electric motor converts electricity into motion.”

He also notes that to calculate the overall horsepower of a dual-motor electric vehicle, the rating of the front motor was added to the rating of the rear motor. “Where some confusion occurs is that in the 85D and 70D vehicles the combined motor shaft power is very similar to the battery electrical horsepower under many normal conditions,” he added. “With the P85D the combined motor shaft power can often exceed the battery electrical horsepower available. The dual motors utilize the battery horsepower in the widest variety of real world conditions.”

Interestingly enough, nowhere in the post does Straubel specifically confirm or correct the 691-hp figure that’s advertised for the Tesla Model S P85D.

[Source: HybridCars]

Discuss this story on our Tesla Forum

  • Mark Wheeler

    This company makes me think of Scam Artists with everything they do.
    Like Apple cell phones a sucker is born every minute!

  • smartacus

    Thank God the horse is not going the way of the Tesla.

  • Alan Dean Foster

    Must be, to buy all those phones.

  • Dominic Brissette

    People completely miss the point.

    The Model S P90D delivers insane acceleration and is faster than any sedan on the market period. Who cares about definition specifics and numbers, where the car DOES deliver amazing performance in the real world…

  • Fast Er

    Who cares about definition specifics and numbers? It’s as if VW says don’t bother about the emissions are way over limits, “because the backseat space is huge”. What has one thing to do with another? You pay and buy a car advertised as having 691 hp and it shows to be missing 20% of those hp. So what did you pay for? Are you Tesla fans that blind? I guess since the “visionary” Elon Musk approved such a thing then it MUST be OK. And it’s NOT the fastest sedan on the market, barley the quickest sedan to 60 mph. It’s a one trick pony, fast acceleration to 60 mph, that is it.

  • Da Botz

    So, the limit is given by the battery ability to punch out more power… given the data, I suspect Tesla would need to make a P110D to be able to fully power both motoirs at their peek.

    I think it is the limit they see for the batteries they can put on the Tesla, for the next few years (no sense in designing a smaller front motor assembly, to have to redo it in a couple of years).

    They could have been more astute and point out it from the start -“the motors are fairly oversized over the battery power output, to allow greater flexibility in allocating the power to the axle with the better grip, and to improve reliability” – 557 HP is still nicer than anything I ever driven.

    On the other hand, battery tecvh improvements are a bit unpredictable… may be a long time, before a Tesla can use all of its motors at full power…