Wow, you already modded the engine after having the car for a week or two? Not worried about the warranty I take it?Yeah the dealer said it takes regular and filled her up with 87. I topped it up with 91 once I hit a 1/4 tank. I only use 94 octane in my Volvo, but then again it is turbocharged and modded. The higher octane makes a noticeable difference.
I believe it's the Volvo that's been turboed and modded.Wow, you already modded the engine after having the car for a week or two? Not worried about the warranty I take it?Yeah the dealer said it takes regular and filled her up with 87. I topped it up with 91 once I hit a 1/4 tank. I only use 94 octane in my Volvo, but then again it is turbocharged and modded. The higher octane makes a noticeable difference.
This topic has been beat to death on the smart car forum -- it actually requires premium, but even it will run on regular. Running premium allows the computer to adjust and you can get a little more HP out of it (are you using it anyway?). My Honda van was the same as the 500 -- premium, recommended [for highest performance (it's a van, right?)] but 87 was OK. I put 180,000 mi on it before the daughter parked it on it's roof in a ditch (everybody was OK they were wearing belts like they were taught). I got as good or better mileage as anyone else and never had ANY problems with it. If you live in the Mountains or really load up your 500 then you MIGHT notice a bit of difference, but my guess is that 95% of people won't notice any difference at all. Now the turbo motor (in the Abarth) should be run on premium due to the higher compression ratios.Most modern performance cars that recommend premium will be just fine on regular, but they may not produce all of the horsepower they can. Octane only reduces the tendency to pre-ignite, so ignition timing can be advanced a little more without pinging. In most of your driving situations, you would not notice a difference in performance. Your engine should have some sort of knock-sensing technology (there are several) that will allow it to adjust to crappy fuel. Ever been to Montana? Last time I was there, regular was 85 octane. Not much power on hills, but the car survived.
The engine has at least one, and more likely two sensors called knock sensors (one high frequency one low frequency) the type of engine knock that you'd be likely to hear (on an old car this would never happen on a new EFI car) is a low engine speed knock if you were lugging the engine, however this is not the type of knocking that is dangerous or damaging to the engine- the damaging knock occurs at high RPM and at a frequency too high to be heard by humans.I just feel safer running premium. Unless/until someone explains to me exactly how the system "senses" and adjusts. Not saying that it doesn't adjust, I believe the modern systems can do this. But is there any damage incurred while "sensing" the octane? I don't think the system is doing a chemical analysis of the fuel. It's probably detecting the pistons getting knocked back sooner than they should be. And if that's how it works, I will pay the extra couple dollars per tank, to avoid that scenario.