I have a 2002 Volvo S40 Turbo and my brother who was using the car was feeling super cheap, and put regular gas in the car. I am aware that with a turbo car you need to have Premium gas (Correct me if I'm wrong). Does this do damage to the car at all. This has only happend once (to my knowledge).

 

It will not hurt the car the car is built with knock sensors.If it felt and pinging due to lower octane gas it would adjust the timing to make up for it.

It might lack a little on the performance side but regular wont hurt the engine at all.

 

Hey, i once by mistake i put the lower grade gas in, i felt little to no diff in driving. However i did i called the dealership just to be safe and they told me to mix in the higher grades in as I go a gallon or 2 to increase the avg octane in the tank. just so you know.

-A1c

 

on my 90 Turbo 740 I put in 89 and its fine.