Yup
I consider that too. Gas weighs 6.5 lbs though, I know this because I'm writing a little app to closely watch gas usage and costs.
Another thing you can do is don't let your car idle. Get in, put your seatbelt on, put your makeup on, put the phone down and then start your car and get moving.
There's a couple of websites about hypermiling (sp?). Their members go as far as drafting semi truck on the freeway.
Oh well, high fuel costs are not much fun so why not make a game out of it?