Understanding environmental impact is hard.
Me and my gas-guzzling mini-van have a much lower impact than most "green car" owners... simply because I drive way, way less than average.
Planes aren't bad for the environment because they burn lots of fuel. Planes are bad for the environment because they are convenient and encourage, enable and create a market for massive amounts of travel.
Switching to advanced, super-clean vehicles won't improve things nearly as much as telecommuting would.