MPG huge fluctuations in the ODOMETER VIEW

The fuel economy that's shown for the three odometer views (total miles, trip A and trip B) is based on the distance traveled in each view. So if "Trip A" shows 10 miles, then the fuel economy that's shown there is based on your last 10 miles of driving. If "Trip B" shows 500 miles at the same time, then its fuel economy display is based on your last 500 miles of driving. When the odometer ("total miles since the car was new") is displayed, the fuel economy is based on the driving you've done since you started the car (i.e., pressed the "Start" button or turned the key to the "Start" position).

The odometer display is always the shortest distance, so it's reading will always vary the most. Let's take an example: you start the car up and the last time you reset "Trip A" was 100 miles ago. So your "Trip A" display shows 100 miles and let's say your fuel economy shows 50mpg. You drive for a mile - the engine is still warming up and so it's not operating as efficiently as it normally does. After that first mile, your odometer display might show 25mpg, because it's entirely based on just that first mile. But if you look at the "Trip A" display, it will still be very close to 50mpg (maybe 49.8 or something...?) because it's based on 101km of driving, almost all of which was done at 50mpg.

Then you hit a long downhill slope for 3 miles where the engine doesn't need to run at all. The fuel economy shown for the odometer view will go up to something like 75mpg because it's based on just 4 miles of driving, most of which didn't use any gas. But "Trip A" will still be very close to 50mpg because that first 100 miles at 50mpg is still a much bigger influence than the last 4 miles have been.

So you'll always see the odometer fuel economy readings vary quite a lot more than the "Trip A" or "Trip B" readings unless you've reset "Trip A" or "Trip B" since you started the car.

 

Nope, only based on how far you've driven since you started the car. That's why it says "from start" just above the MPG number.

 

What really gets my goat is that I left Trip A alone from day 1 when I bought my C new, so I would have that average MPG for the life of the car, then a couple months ago I had some warranty work done, they pulled the battery connections and it LOST IT ALL!!! That is pretty ridiculous Toyota, shame shame! Apparently they were incapable of saving that data to non-volatile memory, grrrrr.... oh well, I'll get over it, not much else I can do.

 

yep, one of life's little detours...