I get 12L/100KM mixed city and highway. I used to get 10L/100KM before I got my 20" wheels.

 

i seem to average 12l/100km, winter seems to be lower, as expected, but haven't run a full tank yet to do the math, the 5% larger tires should help offset the usual worse mileage of winter gas, but the tire spinning and deep snow will not help. once the roads clear up i'll try get some numbers worth bothering with.

 

Has anyone else experienced the kind of results I've gotten with Premium vs. Regular gas? Basically, on any given tank of gas, I get about 150 or so more km using regular (87 octane) gas compared with premium (91 octane) gas. I'd always figure the premium would get better gas mileage because it would burn cleaner since that's what the engine was designed to use but it just isn't the case.

 

No, I haven't because I only use premium. However, if you're seeing that kind of difference either your driving style is very different between grades or there is something wrong with your car, or your calculations. IMO, the different octane levels of gas can't possibly make a 20-30% difference in fuel economy especially moving to a lower grade.

 

^^^^+1, should be the opposite. Gas mileage should improve with Premium.

 

True. Adaptive engine management advances timing to a point just shy of detonation (knock, not ping). This timing gives maximum efficiency and performance. The ECU has to retard timing when you're running lower octane (in order to avoid detonation/knock) which should result in higher consumption due to reduction in efficiency.

Remember that gasoline has the same BTU capacity regardless of octane rating - higher octane just increases resistance to detonation and ping.

 

Yea, that's what I thought too. I thought maybe it was because the gas that's available at Husky and Mohawk are ethanol blended gasoline...well the Premium and mid-grade at least whereas the regular is just..well...regular gas. I shall have to try it out again to see if things have changed.

Maybe I do get on the gas a little more with the premium just because there's that many more horses under the hood... :-D

 

something i've been curious about, how aggressive can the timing get? say it's designed to run at 91, and you fill up on 94, i assume the ecu will push the timing even further, but where's the limit? would there be any point in running higher rated fuel than that? or would the car need extensive modification to take advantage of the anti-knock capacity of the fuel?

though i have to say, at first when i ran reg i didn't notice a difference, but in the cold weather, it's a real dog if i run anything less than 91, and at 94 it's definitely noticeable when it works it's way through the lines.

 

Ethanol has higher octane (actually boosts octane when added to gasoline) but it has lower BTU capacity. Winter gas blended with ethanol will give you worse fuel economy. Makes me wonder if the tree huggers are aware of this fact and whether there's a net green benefit to burning our food.

 

any one notice poor mileage with american gas vs canadian gas?

on the 1100km trip to my sister's place in michigan, we got about 150-200km less on the first return tank from michigan, than on the 3 tanks from ontario, and the van ran miserably too, supposedly the same rating, and it was a big name station too.

maybe another reason we seem to get better numbers up here?

 

I usually make a trip at least every couple of months to Michigan and I have not noticed any change in gas mileage after fueling up there.

 

I average at 24.8 MPG with about 60% Highway and 40% City

 

So could this be the reason I'm getting better gas mileage with the non-ethanol blended regular vs the ethanol blended premiums?

But then again, I've been driving with regular gas for about 8 months now and have consistently gotten better gas mileage then when I was running premiums for the prior 4 months...so it's not really a "winter" thing...and despite what people might think, Calgary, Alberta DOES get hot once in awhile.

Never-the-less I'll fill my next few tanks of gas with Premium 91 from Mohawk and see if things change up a bit. (I'll keep strict tabs on my driving behavior )

 

On any of my US trips I have noticed either the same or slightly better in the US. I actually think many of the road surfaces are superior and offer less rolling resistance.

 

anyone know the tank size of the 2003-2007 G35 6mt coupe? 76L?