When I bought my brand new 56 plate Cooper last year I had already seen a 1 year old Cooper with identical spec. Dealer quoted me a monthly payment of £279 / month for the 1 year old, but I could have the brand new one for £240. Reason was that the guaranteed final value of the older car was far less than the brand new one. Your payments may be high for the same reason, a newer car may cost you less
Monthly payments for PCP are calculated on the Total cost of finance, minus the deposit, minus the guaranteed final value.
Plus I never trust a none MINI dealer to value a MINI as they don't know enough about the options.