[icebraining]

Not having to own a car to travel by car will of course increase driving, or being driven really.

I'm not sure. When you own a car, you pay large fixed costs but your marginal cost per mile is low, whereas with rented cars it's the reverse.

Sure, people who don't own cars currently will probably ride more, but everyone who does have a car now will have an incentive to ride less.

[ghaff]

Your visible marginal cost (i.e. mostly your fuel) may be low but the vast bulk of car costs are proportional to mileage--especially in areas where salt in various forms (winter roads, marine) isn't an issue.

[icebraining]

It doesn't really matter if it's lower than the fixed costs, it matters whether it's lower than these hypothetical rented cars, and most likely, it is.