Well, anything that burns up oil externalises costs a bit, in the sense that we're all going to be equally screwed in the long run whether or not we're the affluent Westerners who did the burning, but I think cars are unusual. Flying, say, is a bit unpleasant for people who live near airports, but it doesn't routinely kill enormous numbers of people who don't fly; likewise (if only because it's not as commonplace) flying doesn't produce an enormous distortion akin to all the shops being in vast out-of-town retail monoliths and half the employers being in the arse end of nowhere; most other processes that burn oil don't spit the end-products out at street level where people are breathing, and so forth.

If I was sensible I would have hired a handcart - some friends of mine moved across Cambridge with one - and of course one doesn't have to be particularly hardcore to move three bookcases a mile by handcart.

[Also, of course, the occasional need to haul stuff doesn't have to be met by you personally. Friends of mine who want bookcases or firkins of beer or exercise equipment moved don't have to own cargo trailers personally...]

On the other hand I eat all the cows I can lay my hands on so I can't really talk.