Since you bought the car from a bona-fide business the sale is a commercial contract. You are therefore afforded protection under the Sale of Goods Act 1979 as amended.
You therefore have the right to reject the goods and claim a full refund or have them repair it for you.
Your grounds for these remedies is that the goods were not of satisfactory quality - probably on safety and durability grounds.
However, a Court may decide (if it gets that far), that taking the price of the car and other factors into account, that it met the satisfactory requirements. My money is on you winning though.