As Karting above has said .. WORM run a indoor WRC championship every summer for Mini bodied micro's ... we use mixed surface with either foam tyres for tarmac style rallies or stretch inner tubes over the foams for more drift style loose surface rallies ..
The loose style rallies are amazing fun, particularly when holding a good sideways drfit
drift style -
http://www.youtube.com/watch?v=TlrxOU6_IMI
foam style -
http://www.youtube.com/watch?v=TEGJQIgY6lg
Mini's like this -
and coming soon Mk2 Escort