snagitseven

I also sometimes wonder if the pump is giving what's labeled, octane-wise. Another reason for going with premium vs. regular. I would rather have the octane be off a some from 93 AKI than to get some gas below 87 AKI with regular.

At least if the tanker is filling the underground tanks while you're there, you know the gas is fresh. Probably doesn't matter if the station is high volume though - less likely to have junk in the station's tanks and probably more often checked by the state inspectors.

MateoA8

One thing to remember too is that the higher the octane the hotter she burns. The arguement that running 87 vs 91 will see a decrease in fuel economy is flawed and unproven. There is probably a negligable difference at best, if any. Performance? Sure. Fuel economy? NO. On a longer trip driving strait down the motorway sans any hills/mountains and maintaining a constant speed (75 MPHish) you'd be fine running 87 any day of the week. Mixed driving conditions in shorter bursts? Better stick with 91.

Anecdotally I run 89 octane in my 03 A4 1.8T under mixed driving conditions 30% City, 70% Motorway, and she never pings at all, goes when I press down on the peddle.

mishar

Hotter yes, because it allows more of preignition. Higher heat means higher cylinder pressure and higher efficiency. That's fairly simple Physics (Carnot cycle).

But if you get detonations, no matter how small, you get extremely hot spots that can easily melt your pistons, cylinder head and exhaust valves.

Wouldn't just a simple logic tell the opposite?

Again, just the opposite. On a long highway drives you have a constant load, while city driving and shorter bursts allows lots of time for internal parts to cool down.