I want to wash my car

if you don't have a car

Yeah, totally coherent.

If I were the type of person who was willing to give AI the benefit of the doubt and not assume that it was just picking basically random numbers

There's a lot of cases where it can be a shorter (by distance) walk than drive, where cars generally have to stick to streets while someone on foot may be able to take some footpaths and cut across lawns and such, or where the road may be one-way for vehicles, or where certain turns may not be allowed, etc.

I have a few intersections near my father in laws house in NJ in mind, where you can just cross the street on foot, but making the same trip in a car might mean driving half a mile down the road, turning around at a jug handle and driving back to where you started on the other side of the street.

And I wouldn't be totally surprised if that's the case for enough situations in the training data where someone debated walking or driving that the AI assumed that it's a rule that it will always be further by car than on foot.

That's still a dumbass assumption, but I'd at least get it.

And I'm pretty sure it's much more likely that it's just making up numbers out of nothing.