from what I've read, there's not much difference between a packed long distance flight and all those people driving the same distance one per vehicle. It's going really far that consumes tons of carbon. (But taking a bus or train gives you the group transport benefit of flying and the lower energy consumption of going by ground. A minivan full of friends is probably pretty fuel efficient too.)

I hope that keeping my car travel to a minimum does something to offset the yearly transatlantic flight to see my family. I'm able to do just about everything except medical appointments and buying gardening supplies by foot or bike here, which wasn't feasible in the US. (Designing towns to be accessible for non-drivers goes so much farther than treating transport as an individual choice, I think.)