10 Cars That Faked Their Horsepower Ratings

A car with wrong horsepower rating isn’t any different than a candy with inaccurate calorie information. Well, maybe in theory, but not so much in practice. Mostly because a few additional horsepower often cost way, way more than a few extra (or a few less) calories.

Carmakers have often reported lower power output figures than their cars actually delivered in the past. That practice saved a lot of money both for them and to the buyers. It was seemingly the easiest way to cheat both the EPA and insurance houses, and outmaneuver their newly imposed taxes on emissions and horsepower ratings. Moreover, manufacturers often adjusted the horsepower in order to achieve more favorable NHRA drag classification. They didn’t lie, however. They only measured power in conditions that were often far from perfect.

And there were numerous ways to do so. One such trick, for instance, was measuring the peak horsepower below maximum engine speed or decreasing the RPM. If a carmaker wanted to achieve the opposite effect, they would simply measure hp at the crank instead of wheels or use the open-exhaust system. Combinations are plentiful and one only needs readjusting one of the parameters in order to tweak the final figures.

Whether it’s the lower or higher horsepower than advertised, such examples are abundant. However, underrated cars are way more common than those that are overrated, so here are 10 such examples. And, before you ask: “No, there are no muscle cars on this list!” We’ve covered that one before.

Any Japanese car with 276 HP

Years: 1989-2005

In what came to be known as automotive version of the “Gentlemen’s Agreement”, Japanese manufacturers decided to limit all of their domestic models to the maximum of 276 horsepower. The reason: they wanted to avoid the horsepower war in a country shackled by rather strict speed limitations. This is the reason why you won’t find a Nissan Skyline GT-R with more than 276 hp although R34 easily made more than 320 ponies. R33 and R32 also pushed north of 276 hp, and so did the R34’s successor – the V35 Skyline (G35 Infiniti). Other such examples are numerous Mitsubishi Lancer Evo’s, Subaru Impreza WRX’s, Toyota Supra 2.5L 1JZ-GTE and 3.0L 2JZ-GTE, third gen Mazda RX-7, etc.

All of these Japanese sports cars made more than advertised 276 hp. And then came the late 2004 when Honda finally broke the agreement. Then new 2005 Honda Legend (Acura RL in the US) was advertised with 290 ponies. Although oathbreaker of sorts, Honda at least chose the right model to dissolve the agreement. You simply can’t point a finger at something called Legend, can you? Not that the rest of the pack felt deceived. All Japanese manufacturers wholeheartedly jumped in on the 300-hp wagon which was sort of a forbidden fruit for them, for way too long.

BMW M5 (F10)

Years: 2011-Present

Current F10 generation M5 officially squeezes out 553 ponies out of its 4.4L twin-turbo mill. This B44TÜ version of the BMW S63 engine uses 10:1 compression ratio and 1.5 bar (almost 22 psi) of boost compared to 9.3:1 compression and 1.3 bar (close to 19 psi) boost of the non-TÜ version of the engine. Moreover, it’s the first BMW M car engine with valvetronic – BMW’s variable valve lift system. Everything would have been just fine hadn’t this setup actually produced north of 600 horses. That’s what people over at iND Distribution claim, at least. They dynoed the stock 2013 BMW M5 and measured no less than 527 hp at the wheels. Add some 15% that went on drivetrain losses and that comes at just north of 600 horsepower. However, 15% rule shouldn’t be adhered to strictly. Every car experiences different drivetrain losses due to different engine, transmission and driveline design.

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