But is it as impressive as the Supra?
When the BMW Z4 and Toyota Supra were both announced, Toyota fans weren't overly impressed that the 3.0-liter turbocharged inline-six shared between the two cars produced 335 horsepower in the Supra whereas the Z4 comes with 382 hp on tap. BMW's 0-60 mph rating for the Z4 M40i of 3.9 seconds was also quicker than Toyota's 4.1-second estimate, but when the Supra was tested in the real world, it actually posted a time identical to the Z4.
It turns out the Supra's engine was underrated from the factory and produced more power than expected on the dyno. Now a Z4 owner named Joseph Hatheway has put his car on the dyno, revealing if all that hatred towards the Supra's output was well-founded.
Hatheway says he did three pulls on an all-wheel-drive dyno and on the first two, the engine suffered from heat soak. After waiting 15 minutes to do the third run, the Z4 put down 362.5 hp and 425.7 lb-ft of torque to the wheels. Just like the Supra, the torque figure was much higher than the 369 lb-ft rating quoted by BMW.
When Car and Driver tested the Supra, it put down 339 hp and 427 lb-ft of torque, both of which are higher than Toyota's estimates. But in this case, the Z4's hp rating was slightly below BMW's estimate. However, if you factor in drivetrain loss, the Z4 actually gets close to the 382 hp rating from the factory.
What these two tests have proved is the ratings from BMW and Toyota mean far less than the real-world results. Both the Z4 and the Supra produce more power than the factory says and both will likely be quicker in real-world performance tests as a result. So if you are in the market for a new convertible, get the BMW. If you prefer a coupe, the Supra is your best bet and you shouldn't pay attention to the factory hp ratings when making your decision.