ok I exaggerated a bit, its more like 10%. They did an article in car and driver on a turbo'd saab and it lost 16 rwhp which is about 20 hp and its rated at 200 hp. So 10% is about right, turbo's require higher octane because the forced induction tends to cause premature detonation alot easier. Anyways they did the test on an M3 since it requres premium as well and it lost 6.6% of its power.

 

with the whole premium gas thing its a MUST they wouldn't tell u to do it if they didnt mean it for a reason. The engine and such need it. Its just like Lexus' they all require premium gas, and if u have the $$ to drive one of those u got the $$ to buy premium gas lol. Its all about PERFORMANCE.

 

ya please don't put regular gas into that machine, if it says premium put premium for sure, like someone else said, you won't only be losing out on a percentage of performance, you'll be burning your engine up...