BMW has released updated acceleration times for their upcoming Z4 M40i roadster.

This week, the 2020 Toyota Supra finally took a bow at the Detroit Auto Show. Not wanting to steal its sister car’s thunder, the upcoming BMW Z4 will instead be revealed later this year. We know it will possess a more powerful version of the same B58 3.0-L turbocharged 6-cylinder engine than the Supra, and so it will be the faster car.

Imagine our surprise when Toyota released the Supra’s specs and said it would accelerate from zero to sixty in just 4.1 seconds. Faster than the Z4’s previously reported 4.4 seconds.

Clearly there was an error here, so BMW has since corrected it. The 2019 Z4 M40i roadster can now accelerate from zero to sixty in 3.9 seconds--a full half-second faster than before.

What changed? Nothing about the car, that’s for certain. More likely is that BMW felt forced to update their previously conservative acceleration figures thanks to the Supra’s impressive 4.1 number, especially since the Z4 M40i produces 47 more horsepower than the Supra.

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While the A90 Supra produces 335 horsepower from its 3.0-L flat-six, the Z4 M40i gets 386 hp from a slightly tuned version of the same engine. While the Z4 weighs about 100 lbs more than the new Supra, that doesn’t account for such a vastly slower 0-60 time of 4.4 seconds.

BMW Z4 M40i Gets Updated 0-60 Times
via BMW

So instead, BMW took their Z4 back to the track and tested it a little more thoroughly.

Of course, these are all estimates, so take them with a grain of salt. Real-world performance will have to wait for both cars to be released.

Acceleration times for BMW’s base-level sDrive30i remain the same at 5.2 seconds. Much like the lower-trimmed Supra, the sDrive30i is powered by a 2.0-L turbocharged 4-cylinder producing 255 hp and 295 lb-ft. We’ll see the sDrive30i release first this coming March, with the M40i being released later this year.

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