We know that higher-octane fuels burn more efficiently. Now the octane debate for vehicles that don't require it is heated and lengthy. Some vehicles have an octane sensor that adjusts timing according to the octane level. I haven't found much talk here about Xylene and I think there is potential for discussion on this site.
This Aromatic Hydrocarbon is basically what fuel companies add to base gasoline to increase octane ratings. I've heard of a guy up in Montana that runs a Corolla on a Xylene blend and gets a significant increase in fuel economy. I've used it to get my fuel up to 100 octane for a 2.0L turbo vehicle.
After signing-up for a commercial account at Sherwin-Williams (free), you can purchase 5-gallon drums of the stuff and mix your own blend, instead of paying for the "premium" at the pump. Granted you don't get other additives to clean out carbon deposits.
I have no need to try it. My car likes 87 octane and no more. Since 91 or 94 or 100 takes longer to combust a lot of the gas would end up exploding halfway out my car or not at all. It's good stuff if you need the higher octane, and it works rather well in your own mixes, but if your car doesn't want it normally it usually won't help. I might think about it if I ever change compression ratios or timing drastically though (I'm thinking timing stuff once I get my damn chipping going, I can chip everything well, just my burner goes blah on me).
I agree with SVOBoy on this one. Higher octane doesn't really burn any better. It will burn better if you have a high compression engine, but that is only b/c the higher octane will retard combustion and make it perform the way the engine is designed.
For a while I was going to do a d15z1 mini-me on my d15b2 block (all honda parts for the non-honda people). After I did a few calculations however I realized that my compression ratio would be about 12.3:1. this would be great if I was running drag races, but I'm not. I figured it would defeat the purpose of the swap (for fuel economy) to modify my engine so that it needs 95 octane to avoid knocking.
Does anybody know if there are any additives other than Xylene that would help boost fuel economy on my 2007 Toyota Corolla? The EPA is saying they're going to put more ethanol in the gasoline for 2001+ vehicles and I was wondering if that kind of additive will help or hurt my fuel economy.
If they do go forward with E15 then there will be the option at the pump, either with a separate pump (like diesel) or a button on the pump (like different octane ratings) so you'll still be able to get E10.
Keep in mind that even if you can find an additive that proves reliably to increase fuel economy, you'll need to get it at a price that pays for itself with that improvement.
Maybe boat gas or racing gas? A few gallons of E0 in a tank of E15 would bring it down to E10.