1.5tfsi poor mpg

[Stevo8v]

So recently had the car in at Audi hamilton for new spark plugs as part of my service and since then my MPG has taken a hit.
A normal trip to work is about 13.5 miles and I pretty much average 52mpg coming home not so much as its up hill mostly. But I now only get 42mpg sometimes less on the exact same trip to work.
I've checked the oil, it's fine. Everything is intact and there's no error codes on the dash. I've scanned with OBDeleven and I've only 1 error with a wing mirror heated glass open circuit.
Any suggestions welcome.. no binding brakes either.
Cars done 83k,

 

[eribaMotters]

The drop does sound a little strange and I typically average 48/52mpg on non rush hour running about in my 35tfsi. Your comment on uphill is possibly more important than you think though. I live in hilly Devon, and from home in Hatherleigh to Okehampton about 12 miles away I typically get just over 40mpg, but on the way back, downhill by 3-400 feet, this rises to over 60mpg.

 

[Stevo8v]

I've had the car for 2,5 years and this is the first time ive had this issue. Im going to double check the front and rear callipers at the weekend and make sure they arent binding

 

[Wibbly]

I know you said you've had it for years, but has this correlated with the colder weather?

 

[NHN]

I've had the car for 2,5 years and this is the first time ive had this issue. Im going to double check the front and rear callipers at the weekend and make sure they arent binding

Get a thermometer gun from Prime, cheap enough & they work, then check all calipers, wheels & discs after a run, that should determine if it's sticking.

Did they do any ECU updates whilst in?

 

[Stevo8v]

I know you said you've had it for years, but has this correlated with the colder weather?

Im not entirely sure, Its something ive ever really noticed during the winters, its only really been below Zero a couple of time and its still pretty mild in Glasgow at the moment.
even using aircon in the summer i never saw this drop in MPG, I did however read that there was a software update that wasn't a mandatory update but did effect.

Usually i get 410-425 Miles per full tank of E10, But only managing 375miles before im flashing red on the dash. which is about 4-5L left in the tank.

Defo something up!

 

[Audi Ashley]

I have literally posted nearly the same issue, poor mpg after service. I wonder if they used cheap plugs and air filter ?

 

[Stevo8v]

Yea I was it was suggested to me that could be one thing they've done, or it might be a spark plug with a slight difference in spark gap to the rest.. it can happen i suppose.

When you say they changed the filter. my dealer refused as it wasn't due at the time i put it in for the service, so they didn't bother.. i check that too cause ive never done it.

 

[Audi Ashley]

I asked and it was due a full service, my thought is that the air filter and plugs are of a less quality than what was fitted when new.

I have been looking to replace the air filter with a Mahle Knecht which I think would be close to the original.

The plugs I dont fancy touching but I am thinking could these 2 effect the MPG or is it the time of year and crappy fuel ?

 

[eribaMotters]

It's a petrol engine, not a diesel, so no dpf.

Colin

 

[CraigM]

My guess would be they've possibly used a thicker engine oil which would cause a decreased MPG.

 

[Audi Ashley]

Put some fuel cleaner in car, I am getting about 40-45 mpg but no more. Wonder if I should drop the oil and put something thinner in. would that help ?

 

[eribaMotters]

I posted above about how hills can effect fuel consumption. Another one to consider is the wind. We drove from Devon into Cornwall to spend New Years Eve with friends, travelling along the exposed A30 into strong winds. I've seldom felt the effects of wind on my A3 but I did last night and saw fuel consumption take a hit from mid 50's to low 40's. Coming back this morning it was showing high 50's.

Colin