Here's a video clip of a 4 yr old driving the Hillclimb...16mb
The track surface is 3/8" MDF painted with flat Latex, to look like a dirt road (it's getting dirtier)
The scenery is styrofoam and plaster cloth. The whole thing takes up 8' x 8' of floorspace.
Two sheets of 1/2" plywood are used as a base and the track comes out of 2 sheets of MDF.
The picture below shows the construction
There is a reversing loop at the top and a good run up and back down is under 25 seconds.