I keep hearing about how environmentalism is so trendy here in LA, but one obvious way to reduce your carbon footprint is to get over in one of the right hand lanes on the freeway and drive 65 mph instead of your usual 78 mph. Watch your tachometer and you'll see a big difference in your RPMs -- there are rapidly diminishing marginal efficiencies in pushing air out of the way as your speed increases, especially if you have an SUV or other non-aerodynamic vehicle. You can drive 15 miles at 65 mph instead of 78 mph and arrive at the same moment if you leave 2 minutes and 20 seconds earlier.
Funny, though, how you never see anybody trendy-looking in the slow lane. I have to drive one long, steep uphill stretch of freeway a lot lately at midday when there's not much traffic. I've found that if I take it at 62 mph the whole way, the automatic transition won't ever have to downshift and push my RPMs through the roof. I've noticed, though, that I'm sharing the slow lane with more Datsuns than Infinitis. Typically, I go up the mountain behind a dilapidated small pickup truck with a lawnmower in the back, while to the left, hand-detailed Volvos and Priuses zoom past us losers.
As far as I can tell, environmentalism in LA is mostly about shopping, buying stuff white people like to flaunt your social conscience and income, about showing the world that you're living life in the fast lane. Driving slower so you can save money at the pump, in contrast, is seen as just sad.