My fabia mpg is dwindling compared to what it was. I can't understand why, what checks can i make before going to the garage?

its colder - uses more fuel.

Depends if it's petrol or diesel engine. Common things are.

1: Air Filter Clogged

2: Brakes Binding

3: MAF dirty

4: Air leak

5: Blocked exhaust

Worth having ECU read for any fault codes. If temperature sender playing up, can lead to over fueling, as the ECU thinks that engine is always cold.

yeah good idea i'll get my mate to plug the vag-com software in this weekend.

sorry its a vrs, so diesel.

1) Standard air filter change interval is frankly ludicrous. @ 40L miles. So if you haven't changed it. Change it.

2) It's colder.... Means the car may be more spritely but tends to use more fuel.

3) It's colder! Check your tyre pressures. I did mine the other day and the fronts had lost close to 20%. I don't check them as often as I should.

4) At some point, the diesel making people switch blends at the refinery and produce a winter blend diesel. This has better low temperature properties and resists waxing. Just doesn't go as far or as fast.

5) I think there's an optimum temperature for economy. Somewhere between 20 and 25 degrees on a spring or summer's day, the car will go miles if driven sensibly.

J.

correct me if im wrong but is there not something added to diesel during the winter months to ensure it doesnt sludge up in cold weather and this has slight negative effects on MPG

nice one might try the air filter too.

Winter diesel gives slightly less fuel efficiency. If you have eliminated all the above mentioned stuff, you may want to try cleaning out the intercooler as well.

Another thing that knocked fuel economy a little in mine was the vacuum control block on top of the O/S front strut. This had started to malfunction in some way (was making a slight buzzing noise when engine switched off). Replacement bought the car back to a more sprightly pace and improved fuel economy.

How many miles has it done? Mine was doing more MPG than the day I bought it with 122,000 on the clock?

Chris

Do we use winter variants of diesel in this country?

I thought the standard grade was adequate with its blend of additives in?

Mine has gone from around 52-55mpg on very long run 2 months ago down to 48-50 on same long run now. As above, its colder, the headwinds are stronger and traffic conditions slower = more congestion = burn more fuel.

Never mind only another 32 days and.............SUMMER'S COMIN!!!!

Roll on the solstice.

quite a few of these threads at moment which is pointing me more in favour of saying its cos its cold. but do check the other things as my journey home at 4c tonight didnt make much difference to mpg however other nights on same journey with nothing to hinder me i can produce less mpg or more.

Don't forget increased consumption this time of year due to more electrical drain ( lights, heated screen etc )

Right actually got some facts and figures for you guys now that will maybe shed some more light on the dilema. I drove down to my mates house tonight a journey on which I can normally easily achieve 60mpg from a cold engine start, on this journey tonight though the engine was fairly warm as I had driven the car an hour earlier. My mpg tonight though was only 54mpg. (Both these mpg figures are based on driving economically at around 55-60mph)

Whilst there we plugged in his VAG-COM software and checked for any fault codes and the only one returned was related to the air conditioning re-circulation which I presume is irrelevant to this mpg issue.

The only problem we could spot was that the oil level was below the hatched area on the dipstick where I believe the oil level should be.

Would this oil level issue be related to the fuel consumption? Bearing in mind its not low enough to bring on the oil light.

I plan to top the oil up tomorrow so hopefully that will shed more light on the matter.

Also with regards to the cars mileage its done 38,000 so I would expect mpg to increase not decrease as the engine wears in.

I would just say it's down to cold temperatures, mine's always more economical in warmer weather.

checked the air filter was changed at 30k so should be good also i've inspected it and it seems ok.

This type of thread is now as common as the "Its summer and hot now, should my car be puffing black smoke out the back?"

It's the cold weather, different blend of fuel. Mine has dropped around 8mpg on the same run at the same speed with the same no traffic or hold ups over the last couple of weeks to.