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I Got 38.8 MPG Today

volvo mpg

What’s the best mpg you’ve seen?

Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process.

In the context of transport, fuel economy is the energy efficiency of a particular vehicle, given as a ratio of distance traveled per unit of fuel consumed. Fuel economy is expressed in miles per gallon (mpg) in the USA and usually also in the UK (imperial gallon); there is sometimes confusion as the imperial gallon is 20% larger than the US gallon so that mpg values are not directly comparable.

MVS Forum Moderator matthew1 says:

I’ve done two full tanks comparing mileage from trip odometer/math vs. the MPG computer. It’s accurate to within a decimal place.

MVS Forum Member tjts1 replied:

Yup mine is also accurate. I pulled it at the JY from a 97 automatic and installed it in our 96 NA 5 speed. Its always within .2mpg of calculate mileage at the pump. I used to compare the two at every fill up but now I’m confident in the number the trip computer spits out.

VCA wrote:
matthew1 wrote:
I’ve done two full tanks comparing mileage from trip odometer/math vs. the MPG computer. It’s accurate to within a decimal place.
…and it will be, unless your fuel level sender goes ape, thinks “empty” occurs when you have 3 gallons left and starts throwing trouble codes :mrgreen:

No. The trip computer doesn’t use the fuel level sender to calculate MPG. It uses injector pulse width vs speed. The car was designed to show empty at 3 gallons. When the tank is that low, you can starve the fuel pump in sharp turns. Its a safety feature. The reason fuel pumps die is because owners repeatedly keep driving after the low fuel light comes on.

MVS Forum Member VCA added:

tjts1 wrote:
No. The trip computer doesn’t use the fuel level sender to calculate MPG. It uses injector pulse width vs speed. The car was designed to show empty at 3 gallons. When the tank is that low, you can starve the fuel pump in sharp turns. Its a safety feature. The reason fuel pumps die is because owners repeatedly keep driving after the low fuel light comes on.
Might be true on the 850s, but on the networked cars (post-99), the long-term fuel economy is reconciled with the fuel level difference over the last 100km. Otherwise, ECM-4050/DIM-0002 gets thrown and the trip computer (I assume) errs on the side of the lower figure. I know this because of the 6 months of throwing that code on my car and being 2+ MPG off (using the same gas pump and computing mileage between tanks). Replacing the sender made the figure agree with the computed economy 😯 . Oddly, the ECM is capable of throwing that code even if you don’t have trip computer software installed.

My MPG gauge is very accurate

2 Comments

Thats actually pretty good, I have a ’96 850 turbo with tire pressure set at 35psi and I average 27 – on 1500 miles per week mixed 75% highway. My 2004 cadillac has a much wider range 26 highway and about 10-12 city so 17 isn’t bad

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