To describe cars and busses going up and down Fifth Avenue,can I say:" Cars and busses were RIDING up and down Fifth Avenue"?
It would be a most unusual way of expressing things.
It's people/passengers/travellers/individuals who ride up and down in buses rather than the buses themselves that ride.
Cars and buses conventionally travel/drive/hurry/move/pass (and many more) up and down.
However, it would not be unusual, after test driving a vehicle with heavy suspension or steering, to say that the ride was heavy/uncomfortable or similar, referring to the way that the vehicle handled.
So, you could talk about vehicles riding, and people would understand you, but it would not be idiomatic.