We guess we now know what's up with GM's dogged determination to use 30 mpg as the benchmark for fuel efficiency — it was all about getting the free parking. That's because Ferndale, the booming little inner-ring suburb of Detroit, has passed a new local ordinance designed to offer yet another reason for fuel-efficiency — free parking. The local ordinance will allow drivers of hybrid vehicles and 30 mpg or better autos, to park for for free at the city's parking meters. Although similar rules have been passed by city councils in New Haven, Conn., Salt Lake City, Utah, and San Jose, Calif. — it's a first for the motor city and its suburbs. But would you expect anything but progressivism from a city that's erected a huge traffic crow's nest in the middle of downtown? We still would — but then again, we know Ferndale.