The BMW M340i is often regarded by BMW enthusiasts as being one of the very best all-around Bimmers on sale, if not the very best. It does everything a BMW enthusiast needs their car to do; it’s fast, comfortable, and as usable as every other 3 Series. Thankfully for us yanks, we actually get the M340i here in the ‘States. But that doesn’t mean our European friends aren’t still doubly fortunate, as they not only get the M340i, they get its diesel-powered sibling—the BMW M340d.
In this new video from Joe Achilles, you get to see which is better, the BMW M340i or the M340d. Both cars are obviously incredibly similar, as they both have the same chassis, the same suspension, the same interior, the same available drivertains, and the same technology. So the only difference between them is under the hood and even that’s pretty similar.
The BMW M340i uses a 3.0-liter turbocharged gas-powered inline-six with 382 horsepower and 369 lb-ft of torque. Its codename is ‘B58’ and is famously one of the best BMW engines in modern history. While the BMW M340d uses a 3.0-liter turbocharged diesel-powered inline-six that makes 340 horsepower and 516 lb-ft of torque and its codename is ‘B47.’ They’re also both 48-volt mild-hybrids after the 3 Series LCI update. In most cases, diesel engines are far more fuel efficient and provide better low down torque, while gasoline engines make more horsepower, rev higher and faster, and make better noises. That all holds true in this case, too. But which is faster?
Achilles tested both cars from 0-60 mph and the results are interesting. The M340i was able to do the spring in 3.92 seconds, which destroys BMW’s claimed 4.6 second time. While the M340d did it in 4.44 seconds, which is still seriously quick but not quite as quick as the M340i.
So which car—and mostly which engine—is actually better? I won’t ruin the full results of the video, as it’s one worth watching, however it really seems that the answer depends on your use case. The BMW M340i is more faster, sounds better, and is likely going to be more fun to use on twisty back roads. However, the M340d gets far better fuel economy, pollutes the air less, and still has a tidal wave of low end torque that makes it fun to drive in its own right. However, I think the real winner here is the European customer that gets to choose between both.