Quote: Originally posted by Danny P on 07 April 2005
On my 172 it reads 2 MPG over ie 35 MPG is 33 MPG if you work it out at the pumps. It is a very good guide.
Thats exactly what I find - that its a bit optimistic and reads about 2mpg over the actual mpg. I always reset it after each fill up too.
How does everyone actually work out their mpg manually? I use this:
1. Brim the tank on fill up & reset trip mileage.
2. Drive for a full tank.
3. Refill tank, brimming it again.
4. Note mileage and amount of fuel used for that mieage, i.e. how much fuel I put in the car at that fill up.
(Always brim it so I know exactly how much fuel was in the tank to begin with).
Now my maths:
(32 / 7) x (no. miles / no. litres) = m.p.g.