You can earn an unlimited amount of £100 rewards for every new car owner you bring onboard.
The owner referral reward is only valid for each first vehicle your friends list on Karshare. Rewards for subsequent (second) onboarded vehicles are not paid towards the referrer and the referee.
Not only this, but if you refer renters you can earn an unlimited amount of £20 rewards too. Find out about renter referrals here.