ORIGINAL: MuggyDude
I know you want 1/10, but look at the 1/16 brushed Slash and E-Revo. They are perfect sized, only go about 20 m.p.h. and they are the most durable trucks I have ever seen! Waterproof too.
Those are very cool and I don't think they'd have any issues running through the yard, in fact would probably go better than my E-Firestorm through the tall stuff. lol The bummer for me about those is they take the small batteries, I would have totally preferred one standard size pack. (I have some nicads/nimhs laying around). Also the price is more than I wanted to spend. But on the other hand I KNOW they would hold up and grow with him. Decisions, decisions...