You're right. Back in the day when I could afford to buy brand name gas, I always got better milage with AMACO premium. They had unleaded before anyone else. They were taken over by BP. Don't know if their gas is still as good as it used to be. They pulled out of CT many years ago.

 

There is no way to tell at the pump where the gasoline came from. Even if you buy gas at an Exxon station, that gas or the oil it came from may not have come from an Exxon oil well. The gas in the distribution pipelines is all the same spec, then the brands add their additive packages before distributing to a local area.

Ethanol has less energy than gas, so you will get less MPG when using gas with ethanol.

http://tonto.eia.doe.gov/energyexpla...gasoline_where

 

I find this impossible. I've run both the Z-tube for 4 years and then swapped back to the OEM G-tube. Absolutely no change in city or highway MPGs.

 

3) Do not get a K&N filter. Just buy an OEM paper filter or NAPA Gold filter (basically the same thing) and replace them often. Nissan MAF sensors are flaky and residual oil from the K&N can collect of the MAF elements over time. There is no performance benefit of a serviceable filter.

7) You can't "tune" the air/fuel ratio unless you plan on buying some sort of engine management system. Replacing the plugs, cleaning the MAF, replacing the air filter, etc can fix the air/fuel ratio, if there's a problem. The only "tuning" a Nissan tech can do to the engine computer is advance the timing by 2 degrees.

 

Changing tire size will affect gas mileage to a degree but that is based on your average speed. If you do a lot of HWY driving then taller tires will net you better fuel economy. If you do a lot of city driving, well, shorter tires might just give you better economy. Its all relative to how you drive, speeds, etc.

 

I just bought an 04 with 147k and the first fill up went really quick. So this morning I checked the plugs, and there were twice the gap on them. So I agree check your plugs.

 

why would i lie? i did realize this and i have been gettin this consistently. the only other change i made is suspention and tires....hmmm.. it may have been tires but idk. Just tellin you my experience with my vehicle. But Daveb you have a non revUp could the z-tube affect ur vehicle differently.

 

There are really way too many variables to really determine real-world fuel economy. You kinda goota take such claims with a grain of salt. Simple filling up at a different pump can hange your numbers because the pump shutoff when full may not be the same as other pumps. Also, nobody drives exactly the same route every day with same weather conditions (hills and tailwinds can help drastically) then it's tough to really claim a 1-2 MPG increase. You could be in a mellow mood one day, and an angry mood the next and that could make a difference too. I can see that much of a difference if it's been a rainy week simply because my driving habits have changed due to the weather.

With the HUGE push for automakers to make more fuel efficient vehicles, i seriously doubt their engineers would leave much off the table if they can gain some efficiency here and there.....especially with CAFE mandating what? 35MPG fleet average in 6 or 7 years?

I realize HP sells cars, and sometimes making these high HP engines fuel efficient has it's trade offs, but sometimes on the internet it's just hilarious to read some of the claims people make with no scientific evidence to back it up...other than doing simple division at the pump. Not pointing out anyone's claims here in specific, but like i said. You sometimes need to take these claims of 1-2 MPG here and there with a grain of salt because there are just way too many variables to say mod x gained y MPG. There isn't exactly a dyno you can strap your car to and get a number for that sort of thing