MPG down after service

[riz]

My MPG has gone down about 20 miles a full tank since my service!!! I drive the same way as i have been and i regularly check my oil/tyre pressures. The only thing i can think of is the aircon, but will this take away 20miles on a tank?

I cant think of anything on the service that could have been detrement to the MPG

 

[Fletcher]

Sounds like the aircon to me.