Although older cars might suffer from more problems than a new car – that it not necessarily the case. On the plus side, a new car does not require an MOT until its 3rd birthday. But the two big negatives for new cars are the depreciation and the servicing required to maintain the warranty.
And if you are not a cash buyer, added to the above must be the interest on any loan. You are also likely to be charged a higher insurance premium, being fully comp. on a new car.
Even on a £10,000 new car, the additional costs over running your 10 year old C3 are likely to be of the order of £3,000 a year. And that will pay for a large number of repairs on your C3.