T Ho

I picked up a 2009 TSX for my daughter a few months ago, and I've noticed that the MPG calculation on the display is quite optimistic. Like 2+ MPG better than calculations. This is my 4th Acura ('02 TL-S new, 06 TL new, 12 MDX new, this one used), and I've never had this issue before. All the others are accurate to within 0.5 MPG or so. Is there any way to tweak this reading to better reflect reality?
Not a huge deal, but if I can tweak it somehow, why not...

fbt

I think most of us accept that these displays are inacurate. On both my Audi and Acura I found them to be about 2 mpg on the high side, compared to filling the tank and recording the data.

opboarding

Mine have been pretty consistent at 1.0 MPG off from what the car says over the past 7 years. I've always blamed it on the acceptable tolerances for the gas pumps. If they can calibrate the pump to the legal maximum percentage error, then why not?

fbt

Let's not forget that if they over estimate the mpg, then the lawyers will sue.

TexasHonda

I also have noticed the same optimistic MPG values on several Acura's.

I suspect the fuel delivery rate is calculated from the mass air flow (which is calculated from MAP and other values) and an assumption of stoichiometric fuel/air ratio. The assumption of stoichiometry would be incorrect and an overestimation of mpg as long as engine is operating in open loop (cold engine). Perhaps this accounts for the overestimates of MPG?

My vehicles show a consistent overestimate of MPG of 5-10 %.. The comparison values from tank refilling suffer from several sources of error of their own; refill level, slope of vehicle, pump cut-off variability, etc.

good luck

tmux

Mine's probably been off by 3MPG before. Was also going to ask how the sensor estimates MPG.