I have noticed that it takes many miles to get the average MPG reading up to over 50 MPG on the maxi, I have a tendency to keep the car running when on the rank due to having to move up quite quickly, the average MPG drops to around 25 MPG, but if I get a nice long run around 100 miles return, as said it takes an age to go back up, could there be a problem???

Edited 7 May, 201313 yr by skippy41

If you are sitting in the car with the engine running then your car is still calculating the average mpg as well as the time duration. Although the fuel used at the "stand still" is low it all counts. That is why when I pull up to lights that I know I will be waiting for a while or have just changed I switch my engine off hence I average nearly 60mpg and can push it closer to 70 mpg if I get really anal about it.

I have noticed that it takes many miles to get the average MPG reading up to over 50 MPG on the maxi, I have a tendency to keep the car running when on the rank due to having to move up quite quickly, the average MPG drops to around 25 MPG, but if I get a nice long run around 100 miles return, as said it takes an age to go back up, could there be a problem???

How "quickly" do you need to move? It is seconds to turn the key and fire it up, with the exception of it being cold/wet I would switch the engine off.

Simple ariithmetic.

While you are stopped with the engine ticking over you are burning fuel at around 0.6 litres per hour and doing zero distance. So nought miles per gallon.

Lets say you have the car idling for 30 minutes then drive for 10 miles at 45mpg. You used 0.3litres during tickover and 1litre driving the 10 miles. So you used 1.3 litres for 10 miles driving which is around 35mpg over the whole period. In this example the period with the engine idling has knocked 10mpg off your economy figure. Look at it another way - every 10 minutes idling uses fuel that would carry you 1 mile (in round figures)

Sitting with the engine idling kills your mpg! That is why the Greenlines have stop start.

Simple ariithmetic.

While you are stopped with the engine ticking over you are burning fuel at around 0.6 litres per hour and doing zero distance. So nought miles per gallon.

Lets say you have the car idling for 30 minutes then drive for 10 miles at 45mpg. You used 0.3litres during tickover and 1litre driving the 10 miles. So you used 1.3 litres for 10 miles driving which is around 35mpg over the whole period. In this example the period with the engine idling has knocked 10mpg off your economy figure. Look at it another way - every 10 minutes idling uses fuel that would carry you 1 mile (in round figures)

Sitting with the engine idling kills your mpg! That is why the Greenlines have stop start.

Mine is not Greenline so that is why I switch it off at light etc.

It also does take ages when started from cold, going strait into a 140 mile run, driving between 50 and 60 mph, driving slower doesn't make a difference