There was probably one entry already listed. But it could be a statistical anomoly, so wasn't listed.

Now, you've got 2 results form different people, so it's more statistically likely to be accurate.

Edited by RobJP on 02/05/2018 at 17:14

I checked the Real MPG for my Car and no fiqures were listed. I entred my Real MPG corrected for Trip Computor inaccuracy (its 5% over). The fiqure I entred was 45.86 mpg and then I checked the main Real mpg lsting and it was showing 43.4 mpg.

How come the differece since mine was the only Real mpg entred?

I suspect the site needs a minimum number of entries before it will produce a verifiable average, otherwise one unusually high or low enrty wouls significantly skew the average. What's happened when you entered yours is that the system now has the minimum number of entries required and thus gave the average of yours plus the rest already on the system. That's all.

Rarely is the trip computer correct, and the percentage its out varies from model to model and car to car, to some extent. Of course, it also depends on what figure you are looking at on the trip computer and when you do so - mine has an 'instant' mpg (well, ltr per 100km [which can be converted]) and an 'overall' figure (essentially all driving since the system was last reset [e.g. the battery removed] - but beware - the trip computer uses a fuel flow meter to calculate the mpg, and they aren't that accurate, as they always underestimate the mileage (fuel) left in the tank.

The best way to do it is to use the 'brim-to-brim' method (the fuel flow meter at the filling station pump is more accurate) and the car's odometer, not the GPS, as it doesn't take into account going up and down hill, which is why, despite the speedo reading constant, the Satnav's reading of your speed drops as you go up or down a hill.