Does anyone know if or how much ethanol is added to the petrol. Have you noticed a change in gas milage as the fuel composition has been changed?

In USA, Arco has sold 10% ethanol for decades. Theoretically fuel economy should go down (since it takes more alcohol than gasoline) however I still got 38 mpg with Arco gasoline. Big deal. It works just fine and costs less too.

I'm just curious about what alcohol does to mpg, since it's supposed to make the mpg worse. 10% may not do it significantly, but some places now 30% or more and still call it gasoline. I believe it's Minnesota where they have a law mandating a high ethanol content.

Basically what happens is the alcohol changes the ideal AF to something in the neighborhood of 13:1 and cars get bad milage. I guess the new vehicles shouldn't have that problem, but for everyone else more fuel usage.

However you want to look at it it's dilluting the gasoline, 1 gallon of pure gas Vs 1 gallon of Reformulated gas - the pure gas will have more BTU's and that what makes it work.

So is reformulated gas really helping anything other than perhaps improving emissions on really old vehicles? It's not cheaper, some of the additives are worse than the problems they solve.

if you use more gas how is that polluting less?

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Fuel economy should be about the same on a properly tuned engine because fuel with around 10% ethanol added will have a higher O2 content so it should all even out. Thats what some of the fuel refiners recon anyway.
There have been some concerns here in Oz about what the Ethanol will do to older style fuel lines and fittings but they go ahead and market/sell it anyway!!!

they are starting to introduce 5% ethonol blend
the V8 super cars are going to be running with the optimax ethonol mix they have had a few headaches with the adhesives in the fuel bladders so they have not started to use it yet.

Ethanol kills old fuel systems. Lower amounts kill slower.

I've just been reading a lot lately about engine chemistry and this is one of the things i'm pondering.

If they're doing it as a way to squeeze ethanol 100% in as an 'alternative fuel' it's not because of mpg or emissions it would have to be a convenience thing. I guess they could evolve into doing more than diluting gasoline.

Maybe my viewpoint is wrong on it. I used to think hydrogen was a good fuel, but producing it was going to have to be done really cheaply, which meant using bacteria, but bacteria don't make hydrogen much, but other things like alcohol are already easy to make. It doesn't solve the problem of making carbon dioxide, but it's a way to use less oil.

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Yep sure does and relates to the materials used - fuel lines etc. Modern Efi lines should cope OK.

Its not hard to rig up an engine/car to cope with methanol/ethanol. Its mainly regard seals,rubbers, pipes etc. My cousin and uncle run pure methanol through their dragster without any dramers. To keep it all lubricated they put a cap full of RP7 into the tank.

once it's pure ethanol i'm fine with that. It's just this interim step with the wanky gas that is annoying.

fear monger ... I've been hearing these "alarms" for decades.

Minnesota is calling for 20% total/average by the year 2013. Big deal. It won't be the only fuel you could buy in MN, there are too many cars on the road that won't run it (like the vast majority of 2006 models). The air/fuel ratio would need to change even for 20%, something current cars cannot do except for flex fuel cars.

Minnesota's action is designed to boost E-85, which GM is talking about quite a bit lately. On the other hand it's about time that bio-fuel was used big time. It'll be great for new cars.

Regarding fuel economy: E85 (15% gasoline, 85% ethanol) is only 15% worse mpg that gasoline, so a mere 20% ethanol as in Minnesota's plan wouldn't lower MPG much. Note that MN has the most E85 stations right now (208 stations) while California has none. There are only 300 E85 stations now out of 200,000 fueling stations nationwide. This is about corn-producing states in the midwest that have methanol factories. reference: Autoweek magazine april 24, 2006 page 18.