Glenn,
Cars are made to work all over the world with varying fuel qualities, being services well,
Never being serviced quality of fluids used and all need to perform as expected.

Tuning a car, any car you improve the performance as it's now mapped for a better quality fuel which in turn will burn better, and can increase power as a by product of better fuel burn as the oils used to service the engine are of better quality. Etc etc (I think)

Look at Africa or any other dive country, cars in a harsh environment with no servicing yet run forever.