Average MPG

[vivavlad]

Does anyone know how accurate the average MPG given in the trip computer are. I have had my MK2 64 plate for a month which started with only 30000 miles on the clock. I have driven about 2000 miles since (delivering) and have averaged 53.3mpg. My previous 1.0 Yaris with 160000 miles averaged a little better but I always felt the numbers were a little optimistic. 

[mpm235]

27 minutes ago, vivavlad said:

Does anyone know how accurate the average MPG given in the trip computer are. I have had my MK2 64 plate for a month which started with only 30000 miles on the clock. I have driven about 2000 miles since (delivering) and have averaged 53.3mpg. My previous 1.0 Yaris with 160000 miles averaged a little better but I always felt the numbers were a little optimistic. 

They seem to be opimistic on possibly all cars, deffinitly most cars pretty much. My 2014 Auris Hybris is about 1.5 to 2 mpg optimistic, my Gen 2 Prius was about 2 to 3, I had a Skoda Octavia Diesel, that was around 5 or 6 and a Honda Accord 2.0 petrol was only about 1 mpg optimistic

[Gren]

It can also depend on your tyres and how much you over- or under-inflate them, as the distrance is calculated from the number of rotations of one of the driving wheels or rotations of the final drive at the gearbox (depending on car).  For the same tyre specs on my Mazda I noticed a difference of about 5 miles over the same 250-mile journey between my winter and summer tyres.  That

2% difference in miles would also account for a difference in mpg if everything else was the same.

[Strangely Brown]

58 minutes ago, vivavlad said:

Does anyone know how accurate the average MPG given in the trip computer are. I have had my MK2 64 plate for a month which started with only 30000 miles on the clock. I have driven about 2000 miles since (delivering) and have averaged 53.3mpg. My previous 1.0 Yaris with 160000 miles averaged a little better but I always felt the numbers were a little optimistic. 

That is almost exactly the average that the memsahib gets in her X. That is verified by tank-to-tank calculations. The fuel figures from the car are, AFAICT, pretty accurate.

[Mjolinor]

5 minutes ago, Strangely Brown said:

That is almost exactly the average that the memsahib gets in her X. That is verified by tank-to-tank calculations. The fuel figures from the car are, AFAICT, pretty accurate.

But subject to the same errors with tyre size as the onboard calculations unless you are using google maps or GPS to give you the distances. 🙂

 

[haelewyn]

My aygoX with standard 18" tyres shows almost perfectly what the real consumption is. 

Accuracy : never 0,5 liter per 100 km off.

General consumption over one year, measured tank to tank over 11.000 km is now 4,9 liter per 100 km. All season included but had an extra winter.

Started driving car on new year 2023.

[Chas G]

Not an aygo but may be of interest to see manufacturers mpg claims v whatcar real life tests.

Yaris Cross and Yaris hybrid did well.

https://www.whatcar.com/best/real-mpg-most-efficient-cars/n14356