Question about a certain episode

[komotar]

Here at my new job we were talking about making a test how higher octaine fuel makes cars more powerfull....

Do you remember that 5th gear show where they had 3 cars and they filled each up with multiple versions of petrol and then measured their power.....I only remember the most powerfull car being the WRX STI and maybe there was a VW GTI or a civic type R in there somehwere... I just know they had 3 cars....

anyway, I can't seem to find which episode that was and it would be stupid to DL like 3 whole seasons

So if anybody has this stuff recorded somewhere I'd be glad if I got some help me finding the right episode...