Does anyone know the vehicle sensors that go into calculating the mpg displayed in real-time and on average? I would assume the miles part comes from maybe the engine or transmission speeds. Is fuel rate directly measured?

 

Due to gearing and idling, the engine is never a good source. The miles is taken from wheel rotation and is prone to error due to size of the wheel [error prone to tire wear, inflation and tire size].

The fuel volume is metered by measuring oxygen before and after combustion.

Real time is sliced into refresh interval and the mpg is displayed for it. Average is the cumulative average since last reset till present time.

The only value I see from this information is that a good driver adapts his/her driving style [and even driving time ... choose a time to drive when the roads are less congested etc] to improve gas milage. I also use this as a health monitor of the vehicle as it is an indicator for efficiency.

Salim

 

Thanks Salim.

I asked because I was wondering if the dash mpg would indicate a fuel leak. From what you describe it wouldn’t.

When I was poking around vac hoses I noticed that the fuel line connection behind the air box wasn’t fully clipped in. Gas leaked onto my hand just by moving lines around! It must have been there since I changed the knock sensors 5-6 years ago, but my mpg has been rock steady at 21+. If there was a leak it was small because I never smelled gas despite it being garaged most of those years.