hastighet
As a native speaker of a language that’s unlike anything, I envy you folks so much. Knowing enough English and German you just look at it, and go ‘aaah, speediness’ (I guess the ‘hast’/‘hastig’ bit is the same as ‘haste’/‘hasty’ in English, and the ‘het’ is the same as ‘heit’ /~ness’/ in German).
You wouldn’t guess the word, but reading it in context is so much easier.
For a second I was playing with the thought: what if this was done for an actual reason? Like, you don’t have a garage, a huge storm is coming, and you don’t want your quad to be blown into someone’s bathroom. Plus, it makes the car heavier as well, so it’s two birds with one stone. But there’s nothing else I could think of (provided it’s not a moron).