A4 TDI 143 fuel economy

GTE

Howdy,

The A4 B8 TDIs have a reputation for underperforming with respect to their fuel economy. Not just in terms of what Audi say they will get, of course that figure is ambitious, but even compared to previous generations of TDI.

For example, when I got 2013 A4 in November, I found it hard to get any better than 42MPG where 2000 Golf could consistently get 50MPG. Once things heated up for the Summer, I am now hitting 50MPG with ease. This is an experience that many drivers notice on the Audi forums, too.

Would anyone have any answers as to why the MPG suffers in the cold on this engine? I had an idea to install an aftermarket air filter which would take its supply from within the engine bay. It was just a thought that the warmer air intake would help but the idea is not born out of anything concrete. Once I read up on it, I read that engines prefer the cooler air.

Any ideas?
Thanks

Truckermal

The wife has a 151 and rarely gets over 40 MPG and by **** it's so dead to drive I hate the bloody thing! My 3.0 petrol gets 30 MPG on short trips! She had a B6 Passat before with loads of power and it was always 55 MPG..

I reckon a good 'remap would sort it but ours is still under warranty.

ION08

bbk wrote: »

Howdy,

The A4 B8 TDIs have a reputation for underperforming with respect to their fuel economy. Not just in terms of what Audi say they will get, of course that figure is ambitious, but even compared to previous generations of TDI.

For example, when I got 2013 A4 in November, I found it hard to get any better than 42MPG where 2000 Golf could consistently get 50MPG. Once things heated up for the Summer, I am now hitting 50MPG with ease. This is an experience that many drivers notice on the Audi forums, too.

Would anyone have any answers as to why the MPG suffers in the cold on this engine? I had an idea to install an aftermarket air filter which would take its supply from within the engine bay. It was just a thought that the warmer air intake would help but the idea is not born out of anything concrete. Once I read up on it, I read that engines prefer the cooler air.

Any ideas?
Thanks

Depending on the sort of driving you're doing, 42mpg average wouldn't be too bad.

Are you just reading these figures off the OBC or are you brimming and doing your own maths?

Truckermal wrote: »

My 3.0 petrol gets 30 MPG on short trips!

Find that hard to believe to be honest? what car is it do you mind me asking?

GTE

ION08 wrote: »

Depending on the sort of driving you're doing, 42mpg average wouldn't be too bad.

Are you just reading these figures off the OBC or are you brimming and doing your own maths?

I was doing 40ish-mpg average on the 5speed 90hp 00 Golf TDI with a lot of motorway driving at 130kph with the revs at 3000, so the same again with the A4 with revs well below 2000 has been disappointing. Then the weather warms up and I begin to hit 50-55mpg on the same journey, and I'm much happier there. This is why I raise the question of the effect of engine bay sourced air.

My figures are based off the trip computer, after a few trips where my maths and the trip comp matched.

bazz26

The A4 is a bit heavier than a MkIV Golf, it's not really a fair comparison.

Cee-Jay-Cee

bbk wrote: »

Howdy,

The A4 B8 TDIs have a reputation for underperforming with respect to their fuel economy. Not just in terms of what Audi say they will get, of course that figure is ambitious, but even compared to previous generations of TDI.

For example, when I got 2013 A4 in November, I found it hard to get any better than 42MPG where 2000 Golf could consistently get 50MPG. Once things heated up for the Summer, I am now hitting 50MPG with ease. This is an experience that many drivers notice on the Audi forums, too.

Would anyone have any answers as to why the MPG suffers in the cold on this engine? I had an idea to install an aftermarket air filter which would take its supply from within the engine bay. It was just a thought that the warmer air intake would help but the idea is not born out of anything concrete. Once I read up on it, I read that engines prefer the cooler air.

Any ideas?
Thanks

Cold air is denser and so the MAF or MAP sensor sees more air and fuels accordingly. The more air in the system the more fuel is used.

My 2.0 petrol car struggles to do 28mpg (all short 8kms journeys) in winter but does 32mpg in summer. It'll do 40mpg on a long run and I've seen 46mpg on very long runs keeping it around or under 100kmph.

GTE

bazz26 wrote: »

The A4 is a bit heavier than a MkIV Golf, it's not really a fair comparison.

Its certainly heavier, though I have to disagree; the comparison of fuel economy is fair in this case given that late Spring MPG noted for journey x in the A4 was 50-55mpg but 42mpg in anything below, roughly, 15 degree ambient temperature. Journey x in the old Golf was consistently in the early 40s.

Once again, this is why I am raising the question here about what effect would swapping the air intake from external to engine bay air possibly have on fuel economy. It seems a bit simplistic to my mind that sourcing warmer air from the engine bay would help but its a situation I'd like to figure out and better understand.

CIP4

Just looked back at fuelly my 09 A4 143 when I had it used to average 44.6mpg lowest 41mpg the highest 48mpg. Regardless of the weather there wouldn't of been a hope of it doing 55mpg even the 48 was once off.

corks finest

CIP4 wrote: »

Just looked back at fuelly my 09 A4 143 when I had it used to average 44.6mpg lowest 41mpg the highest 48mpg. Regardless of the weather there wouldn't of been a hope of it doing 55mpg even the 48 was once off.

Expected more, lovely looking motor

snaps

This thread makes a lot of sense. Ive a TDI 140hp Touran, I now live in Poland and wondered why in the winter my fuel consumption was around 6l/100km compared to 5l/100km in summer. Ok, Our weather is more extreme, summers get up to 40c and Winters -30c.
I know winter tyres use more fuel too.

GTE

The temperature sensitivity of this generation TDIs with respect to fuel economy is a talking point in the Audi forums.

AlanMcC23

Normally getting 48mpg on my 177bhp a4 auto 2012

snaps

I actually thought that turbo charged engines preferred cold air? Thus the job of the intercooler?