Hmmm, what's going on?

Just had my 2007 (57) PD170 TDi vRS serviced at a main dealer, it was only a minor service so involved oil, an oil filter and not a lot else.

My MPG has always been rock steady (manually calculated each time I refuel) at 48-49 MPG.

The last two tanks since the service have both been 44 MPG.

Same brand of fuel, same journey (140 mile round trip commute) but less economy?

Now here is the BUT!

They also performed a forced regeneration on the DPF (Diesel Particulate Filter) as I'd had a faulty sensor replaced a few weeks earlier that was (they think) preventing the DPF from regenerating properly and caused the DPF light to come on (only twice).

I put the low MPG on the first refuel down to the fact that the forced regen will have likely drunk a good chunk of fuel sat in the workshop, however after a second refuel it's still just as bad.

Could either the forced regen or fresh oil have affected the fuel efficiency of my car?

Check oil level?

Check tyre pressures? Skoda had a habit of helpfully dropping my tyre pressures to about 25psi for some strange reason.

Just been to check my tyre pressures, they were out by 0.1 BAR all round.

Inflated them as per the pressures on the inside of the fuel filler cap to 2.0 BAR (front) and 2.1 BAR (rear).

I'm assuming that this won't have affected my MPG by as much as the 5 MPG loss I'm seeing?

Will wait for the engine to cool and will check the oil level too...

Try higher tyre pressures, i run 2.4 bar up front in my PD170 mpg isnt calculated as accuratly as you but definitely drive better