Guess how many miles per gallon those yellow Crown Victorias get? About 10 to 15 mpg. That’s on par if not worse than an SUV. But things are changing. Bloomberg proposed this morning to require all new vehicles entering the fleet to get at least 25 mpg, then 30 mpg the year after. One complaint: it won’t take effect for another year and a half, not until October 2008. Still, it’s a great, long-awaited move.