A sure sign spring is here: The area's drive-in restaurants start getting busy again. Take Mr. G's Fast Lane on Baltimore National Pike, for instance. On a recent Sunday afternoon, the couple manning the grills and ice-cream scoopers had their work cut out for them trying to keep up with a small but steady stream of customers looking for cheese steaks, Italian subs, root-beer floats, and the drive-in's legendary onion rings. We popped in, hoping to catch a quick bite, which turned into a 20-minute wait for food. No matter: When our pile of subs, steaks, and rings finally arrived, they were just what we expected from this old-school roadside stand. A couple of greasy, overstuffed six-inch cheese steaks--one plain ($4.49) and one mushroom ($4.89)--for the main course, two small orders of onion rings ($1.69), and two thick vanilla shakes ($1.05). And those onion rings are astounding--huge, fluffy, dipped in Mr. G's super-secret batter, and lightly fried, the things are pretty much a meal in themselves. And they're best when eaten right out of the brown paper bag they're served in, sitting at one of Mr. G's roadside tables with a clear view of the traffic moving down Route 40.