Yo Pearson, I've seen that. Was it the Yellow Lakota River Guides Hummer? They shuttle gapers, er, tourists up to Piney Lake, a ways up a logging road in the winter. Those tank tread things are pretty bitchin, I'm supprised that people in Cherry Creek aren't sporting them on their Hummers yet.
Free parking in Vail you say?! Only in summer, if you are taking about the parking structure. There are some outlying areas at trailheads, and parks and stuff where you can park and ride the bus. You can park on the road in front of Safeway in W. Vail and ride the bus, but I think only F-Sat. Frontage Road is only available once the pay lots are full.
Here's the secret map of free parking (but not very convieient)
You can buy an annual parking pass for like a $G or something for the parking structure (not recommended!)
I don't even hardly go to Vail for this reason any more. I can park for free at the Beav and ride a bus up like 5 minutes, or the Arrowhead lift has free parking, and I live 5 minutes away. There is some really good lift accessed/hike-to backcountry from the Beav (I'm still learning, so I don't have all the info, but use Avy gear, even if it looks friendly and has tracks on it).
Edit> P.S. In the structures it is free for first 90 minutes (or something like that) and free after 5. If you party in the village, find a cop (they're everywhere), and they will give you a free pass to leave your car overnight till 11 for free, otherwise you must drive drunk (please don't) or pay $16 (also bad option) or whatever the rate is.