My Reported MPG has Suddenly Decreased by 2.5 mpg

[Don Stouder]

I have owned my 2019 RAV4 hybrid for almost 3 years. During all of that time, my NAV system has reported slightly over 41 mpg for both city and highway driving.

My driving habits have not changed. I have about 30K miles on it. I had a minor maintenance a couple of weeks at my local dealer. Now the 41+ mpg has been reduced to 38.6 or lower regardless of the type of driving I do.

Why? Any ideas? As far as I know my tire pressure has not changed.

[Gray86]

E10 fuel, cooler weather, or driving into the wind more, could contribute. . . As well as tyre pressures 

[Bernard Foy]

Hi Don, welcome to the TOC forum. It’s not a huge drop in mpg, and can be attributed to several factors or a combination of factors mentioned by Graeme.

[Cyker]

Check your tyre pressures - I tend to run them high but no matter how many times I tell them to leave them alone they always drop them to 32psi.

Also check your paperwork to see what oil they used; If they put in thicker oil that can affect it (Was a common problem a decade ago but less so now).

If this is the first tank after the service I'd disregard it and wait until your next fillup to see what the average is, unless you're not resetting your average mpg between fillups, in which case this dip is probably just from them leaving the engine running during the service, as that is also a thing they seem to do. It should slowly creep back up over time or you can reset it.

[George Dodds]

I think it’s the new E10 petrol as my average MPG, according to the display  has dropped since using it. 

[ernieb]

+1, E10.  You could check it out by switching to the premium E5 when the tank is low and see if it comes back to the old MPG.

[FROSTYBALLS]

Think the OP is based in the US - so their fuel consumption equates to approx 49mpg (Imperial). The US have had the equivalent of E10 available since the mid 70's.

[ernieb]

2 hours ago, FROSTYBALLS said:

Think the OP is based in the US - so their fuel consumption equates to approx 49mpg (Imperial). The US have had the equivalent of E10 available since the mid 70's.

Thanks missed the location.