Session lasts up to 90 minutes
Race up to 40 mph
Includes summary of lap times
Groupon voucher is £19.50, the deal apparently is worth £48. Voucher is valid Sun-Fri, midday-midnight.
The track at Colnbrook (http://f1k.co.uk/heathrow/track-info/) is 450m long, and features a 100m straight, and they use 200cc karts.