Average consumption display screen

[John Archer]

I have had two instances of the average consumption display giving wildly fluctuating figures in my 2018 Polo SE - up to 300 mpg in some cases. If I change to another screen for a few days and then revert back to the average consumption display it is working perfectly. Is this something I should worry about or not. My brother has a 2016 Polo SEL and has experienced a similar problem.

Any help or info would be gratefully received.

[monkeyhanger]

I have had two instances of the average consumption display giving wildly fluctuating figures in my 2018 Polo SE - up to 300 mpg in some cases. If I change to another screen for a few days and then revert back to the average consumption display it is working perfectly. Is this something I should worry about or not. My brother has a 2016 Polo SEL and has experienced a similar problem.

Any help or info would be gratefully received.

Sounds to me like you're looking at instant mpg, not trip average. With trip average, you get a representative mpg value for your journey, which changes over the course of the journey, generally creeping up from a very low value at the start of the journey to something reasonable at the end.

On instant mpg, mpg fluctuates constantly, based on what is happening in any given instant. Driving along and take your foot off the accelerator and it'll head towards 300mpg, put your foot down hoing uphill and see it drop as low as 4mpg, but generally bouncing between 20mpg and 80mpg.

[SRGTD]

In my previous generation Polo, the car’s computer resets the long term average fuel consumption data (mpg, hours driven, miles driven) after 100 hours of driving time. I assume the current Polo also does this, so if the wild fluctuation In average mpg you’ve referred to has happened twice during your ownership of your car, it could be when the long term average fuel consumption data has reset itself - this can be confirmed by checking the long term total miles driven and hours driven - if these figures are low, then a reset has happened recently.

I checked my mpg just after the auto-reset happened on a previous occasion, and because I was mid-journey at a steady cruising speed within the legal speed limit with the engine fully warmed up when the reset happened, the display was showing an average mpg for the handful of miles covered since the reset happened that was significantly better than I’d ever expect to achieve in my wildest dreams! It soon reverted back to a more realistic average mpg as the long term average miles and hours driven increased over the next 100 hours driving cycle.

If you and your brother (also a Polo owner - 2016 previous generation model) have both experienced this, then as monkeyhanger has suggested, you’re both either looking at the instant fuel consumption data, or it’s the long term data re-setting itself after 100 hours of driving time.