Naaaah! It's never too late to resolve to drive less and use transit more. If you intend to drive less in 2008, please post your resolution in the comments.
Mine is short and sweet: I will live car-free at least 100 days in 2008. Every three or four days (at least!), I will either walk, take the bus, or bike to get wherever I need to go. That's probably pretty close to what I managed in 2007, but this year, I want to make it official.
If that seems too drastic to you, consider leaving your car at home one day a week - or even one day a MONTH. Every little bit helps - but the more you can do, the better