[The Handbrake]

Track day participants are liable for damage to their own cars, regardless of fault. You sign disclaimers to this effect before going onto the circuit, so its not compulsory but highly recommended. Daily track-day cover will cover accidental damage to your vehicle whether the accident is caused by you or by another individual on the track. If you crash into someone else they are not covered unless they have purchased their own track-day insurance. Hence without taking this extra cover it's a gamble on your wallet.