Vehicle falling over on landscape - friction too high

I’ve imported the vehicle from the adv vehicle example.

When moving to 4.15 the physics became pretty wobbly. With some tuning (heavier vehicle, lower power, lower friction levels, applying a COG offset in the physical mesh) it’s fairly drivable on my flat road material but falls over steering offroad on a landscape mesh.

The falling over seems to be due to excessive tyre friction but I can’t work out where it’s getting the high friction from.

In the landscape details I’ve tried setting the Default Phys Material, and leaving it “None” (hoping that means it falls back to the physical part of the visual material).

Placing a cube with the same material on it and the car behaves. And I use the physical material on a spline road that also behaves appropriately.

Any clues to where the landscape material gets its friction?

And of course right after posting I found the answer.

Enabling overlap events fixed the friction level!