Lease cars, its homebrew all the way.
Its not as though supermarket petrol is going to screw the car up so bad that you'll end up stranded at the roadside.
If there is any benefit from running fancy fuel, its about extending component life and in 2 years, you don't care because its a) not ever going to cause a problem in that time b) 100% definitely not your problem from month 24 onwards.
Save your cash, buy more cake instead (and fill the cubby hole up with crumbs for the next owner)