Here's some of that "no evidence":
Thanks for posting the link--I would have had to go looking for it or something like it. This isn't something that is completely unstudied.

However, I have to say that I don't think that Detroit's transportation costs are the main reason houses have been traditionally relatively cheap. That is because there are no barriers to supply, because there is basically no regional planning process and no limit to the number of enormous roads the state is willing to build into the middle of nowhere to support more building, and there are no natural constraints to expansion in any direction but Canada.

The causation runs in the other direction--sprawl increases transportation costs, because you need more cars, the cars have to go farther, and because you have to finance all the roads. Cars have a lot of benefits, but as a transportation system they are pretty expensive.