For me it depends on how you came across that £45k.
Scenario 1 : You earn £22.5k per year, you live in a tent and don't eat and within 2 years you have £45k in the bank. In this scenario I'd recommend none of the cars as any big bills will ruin you.
Scenario 2 : You earn £45k per year, live somewhere cheap, don't spend much and have say £22.5k disposable income per year so you manage to save £45k over a 2 year period. In this scenario I'd recommend the most sensible car of the bunch as you don't really have enough disposable income to have enough spare if say a Ferrari needs a £25k gearbox.
Scenario 3 : You earn £500,000 per year and therefore can afford to drop £25k on a gearbox should you need to. In this scenario you can buy what you want but if that huge bill does pop up it might not ruin you financially but it will still leave a bad taste in your mouth.
Obviously there are many possible scenarios and I don't know what your situations is Gibbo but as many have said already, buying the car is only the start, the last thing you want is to be afraid to use it because it could bring you a 5 figure bill at any point.