What is the optimal speed for fuel-efficiency for my car? Do I really have to drive 55? [more inside]
posted by scblackman on Jul 11, 2008 - 18 answers

A flurry of interrelated USA speed limit questions: [more inside]
posted by vanoakenfold on Aug 22, 2006 - 22 answers

I was in Mountain View recently and noticed speed limits painted directly on the streets. Anyone else seen this kind of thing? [+] [more inside]
posted by Jeff Howard on Dec 27, 2004 - 9 answers