Matt Robinson profile picture Matt Robinson 5 months ago
DIY

How Much Faster Is AWD In The Wet And In The Dry?

Tyre Reviews did multiple back-to-back wet and dry tests in a BMW M5 switching between 'RWD' and '4WD' modes to see just how much difference the system really makes

Remind me later

The super saloon power war was always going to lead to the near-necessity of all-wheel drive. There’s only so much grunt you can be sent to the rear wheels before traction becomes an issue even in bone dry conditions, so it’s no surprise at all to see the latest Mercedes-AMG E63 and BMW M5 drive the front wheels too.

Even the G80 M3 is available with an ‘xDrive’ system now, and like the setup on the bigger M5 and the E63, it’s switchable. Systems like these finally allow us to answer the AWD vs RWD question with all of the variables taken out - you can have the same car doing one lap with all wheels powered, and with a few button pushes, the next with only the rears getting torque.

AWD is always going to be faster in the wet, and it should usually have the legs in RWD in the dry, too. And not just for mere mortals - I remember asking the pro drivers BMW brought along to the G30 M5 launch a few years ago, and they insisted AWD was quicker. But by how much? Up until now, we haven’t, as far as we can tell, had a properly geeky, in-depth comparison. Happily, we know someone who’s done just that - Tyre Reviews.

RWD mode certainly can't be beaten for outright fun.
RWD mode certainly can't be beaten for outright fun.

Using the same fantastically nerdy attention to detail he adopts for his tyre tests, Tyre Reviews’ Jon Benson took an M5 Competition and put it through various trials at Horiba MIRA. We see the car do multiple 0-60mph tests in the wet and the dry and using both ‘4WD’ and ‘RWD’ modes, followed by a wet handling lap using the same settings plus the more rear-biased ‘4WD Sport’ option.

The grand finale at the car development facility involved a dry handling lap, which does indeed show rear-wheel drive to be the slowest option, along with the one that requires the most effort, and arguably the one that provides the most fun. As for whether 4WD or 4WD Sport came out on top, and gaps between the modes, we’ll let Jon take you through that.

Were you surprised by the results, or not?