Premium gas less than $3
12-20-2014, 07:32 AM
#32
12-20-2014, 06:59 PM
#33
I dunno. For whatever reason regular gas is usually less than diesel in SLC, but this is as low as I've seen for premium in a long long time.
12-21-2014, 09:22 AM
#35
AudiWorld Super User
newmoon-
A "flexfuel" engine means, among other things, that all of the engine components have been designed for continuous duty with the range of fuels specificed. For instance, a "rubber" fuel hose in an ordinary car will crack and rot from prolonged contact with E50. A flexfuel engine designed to work with E50 will be made with different "rubber" parts, that will not be harmed. That's one part of it.
Another major part of "flexfuel" means the ignition (spark timing) tables in the ECU will be extended over a wide range, because each fuel type has a very different combustion speed and the spark timing has to be altered to make efficient use of the fuel. In blown engines (super or turbo) the ECU also needs to know what boost can be applied and it may have other factors added in, so a genuine "flexfuel" engine literally has the extra wee brains built in to compensate for the differences in fuel, and take advantage of them.
You could easily manually re-tune a 1968 Detroit engine from any of the big three to compensate for fuel type, fiddling with the timing and dwell on the distributor until you got results you liked. But our flexfuel engines are supposed to be doing that all the time, compensating for fuel type, temperature, humidity, barometric pressure, load, and perhaps even the type of music being played.(VBG)
That's why I strongly suspect that the advice to use premium is mainly, bunk. For everyday driving? It may make owners feel they are superior because their cars eat only the finest fuel...but that's like telling me a Gucci wallet will make my credit cards more worthy. As they said on the tv show, "Homey don't think so."
My highway results are pretty much the same as yours: No difference in the feel, or the numbers, as far as I could see. (Which is how a "smart" ECU should be running things!)
A "flexfuel" engine means, among other things, that all of the engine components have been designed for continuous duty with the range of fuels specificed. For instance, a "rubber" fuel hose in an ordinary car will crack and rot from prolonged contact with E50. A flexfuel engine designed to work with E50 will be made with different "rubber" parts, that will not be harmed. That's one part of it.
Another major part of "flexfuel" means the ignition (spark timing) tables in the ECU will be extended over a wide range, because each fuel type has a very different combustion speed and the spark timing has to be altered to make efficient use of the fuel. In blown engines (super or turbo) the ECU also needs to know what boost can be applied and it may have other factors added in, so a genuine "flexfuel" engine literally has the extra wee brains built in to compensate for the differences in fuel, and take advantage of them.
You could easily manually re-tune a 1968 Detroit engine from any of the big three to compensate for fuel type, fiddling with the timing and dwell on the distributor until you got results you liked. But our flexfuel engines are supposed to be doing that all the time, compensating for fuel type, temperature, humidity, barometric pressure, load, and perhaps even the type of music being played.(VBG)
That's why I strongly suspect that the advice to use premium is mainly, bunk. For everyday driving? It may make owners feel they are superior because their cars eat only the finest fuel...but that's like telling me a Gucci wallet will make my credit cards more worthy. As they said on the tv show, "Homey don't think so."
My highway results are pretty much the same as yours: No difference in the feel, or the numbers, as far as I could see. (Which is how a "smart" ECU should be running things!)
12-21-2014, 09:53 AM
#36
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And this is where I wish I'd stuck with the boring UK A6 forum, envy of the U.S.! The tax alone on a gallon of UK fuel is $4.35 a gallon before anything else is added. The current price per gallon in the UK is $8.15 per gallon, which audi forums over here are heralding as an 8 year low! No wonder we all drive diesels!
12-21-2014, 11:08 AM
#37
Because of the much lower energy density of E85 vs E10, a car that gets 21mpg with E10 will get about 15mpg with E-85. That means to travel a distance, say 10,000 miles, it will take ~40% more E-85 than E-10. (476Gallons--E10, vs 665Gallons--E85)
12-21-2014, 02:12 PM
#38
AudiWorld Super User
"The tax alone on a gallon of UK fuel "
And in the US, instead Congress plunders the fuel tax accounts and lets the roads and bridges collapse. Taxes, selective taxes, misused taxes....good foster for a day in the pub but nothing to do with engine and fuel performance.(G)
And in the US, instead Congress plunders the fuel tax accounts and lets the roads and bridges collapse. Taxes, selective taxes, misused taxes....good foster for a day in the pub but nothing to do with engine and fuel performance.(G)
12-29-2014, 08:35 AM
#40
AudiWorld Senior Member
Yup. Quite the kickback to the corn lobby.