PCP to bank loan.

macman

Even if you don't want the car, pay the balloon, avoid the excess mileage charge, and then sell it yourself.

[Deleted User]

Why only 5 years anyway? Modern cars can run fine for much longer than that if looked after properly. There is no such "cost" as depreciation if you run the car for a good length (talking much more than 5 years) - I'm still waiting for the bank of depreciation to send me an invoice for my new car bought 6 years ago, something self declared "experts" claim is a major cost as they all assume you will want to sell the car after a short period, I suspect I will be waiting until my death bed to ever get a bill for that! 

ian16527

Are you intending to give the car back at the end of the PCP? Then the mileage will matter. If you trade in or pay the balloon and sell it privately then the mileage will not matter(in PCP extra mileage costs anyway).
Just trade it in and get the car you want. You may have to stump up some more deposit depending on how much you put down on this one and how much is left on the deal.

Aran76

Ending a PCP within the first 2 years is nearly always a bad idea as this is the fastest period of depreciation, you will almost certainly be in negative equity. 
Ultimately it is your decision, if you want to switch now for the larger diesel car then, thanks to the advice here, you are fully aware that it is the most expensive option available to you.