2019 BMW 540d vs. Mercedes CLS 400 d: Inline-6 Acceleration Test

But BMW is the king of inline-6 diesel engines, and we're not just talking about the quad-turbo M50d setups. No, if you don't want to worry about heat problems and all that, you can still get a lot of performance out of the 540d with its twin-turbo configuration.

The motor is good for 320 HP and 680 Nm, which doesn't sound as hot as the 340 HP and 700 Nm offered by the Mercedes CLS 400d or indeed the E-Class for that matter. But the official numbers also state the 540d sedan is 0.1 of a second faster than the sexy four-door: 4.9s vs. 5.0s. At the top end, though, the extra power and torque help the CLS out.

Basically, both offer hot hatch performance but need two more cylinders due to about a half-ton more weight. The way they drive is different to a Golf R, though. The experience is dominated by excessive torque and luxurious neutrality from the chassis. It's not going to be straining at the leash.

And out in the real world, the same kind of thing happens. AutoTopNL posted one of their usual tachometer comparison videos where it's pretty clear the BMW is a little faster. Not by much, but enough to make you wonder what the point of a four-door coupe is. By the way, both models only come with all-wheel-drive right now, in case it's not clear.

The prices will make you wonder even more. While the BMW M540d xDrive starts at €67,000 in Germany, the CLS 400 d is offered at €72,500. Typical Mercedes. On top of that, you'll probably need a body kit and some suspension upgrades.