What affects MPG???

[Johnjones]

I have an Audi A4 1.9 tdi sport estate.
It does 47 mpg on motorway runs...Not bad, but I was hoping it would be a little better. I do 75- 80 mph all the time and accelerate gently. What can affect the MPG? (Apart from the obvious ones like tyre pressure, poor running, etc.) It runs smoothly with no fault codes or known faults....Could the MAF or MAP cause this without symptoms??? The coolant sensor was recently changed for one off ebay and the thermostat was changed too....it now sits at 90 degrees most of the time.

 

[stu_m]

if your getting 47 at 70-80 then theres nothing wrong there its about right

try slowing down to 60-65 and it will increase

when a maf is on its way you dont get no difference in the drive

the cold effects it too

 

[Johnjones]

if your getting 47 at 70-80 then theres nothing wrong there its about right

try slowing down to 60-65 and it will increase

when a maf is on its way you dont get no difference in the drive

the cold effects it too

Thanks buddy! Is it worth changing the MAF or should I wait until mpg drops substantially?

 

[stu_m]

I would get it checked with VCDS first if you suspect it is bad

 

[BahnStormer77]

sounds about right... I bet you get around 55-60mpg at 60mph, so try slowing down if economy is THAT important.... personally I'd settle for 47mpg at that speed.

I get about 60mpg at a steady 50mph, 40mpg at 70mph, 35mpg at 85mph and 30mpg at 100mph.

 

[demus]

All big electrical loads will drop it too, demisters, lights, fans etc.. all the stuff you need this time of year. 47 isnt far out, most I've ever had from mine is 50..

 

[Johnjones]

Sorry guys, i should have said i'm getting 44 mpg at 70 mph....I'm wondering if the Maf might need changing?

 

[Johnjones]

Even at 60 mph, it still stays late 40s on the trip computer....I don't have any fault codes. Are tests any tests or easy parts to change to see if that helps???

 

[stu_m]

forget the DIS work your mpg out tank to tank

 

[Johnjones]

Yep I did that....590 miles and put 60 litres in...= 43.76 mpg. That was mainly motorway at 75 mph.

 

[fallmonk]

How much fuel economy do you think you loose with keeping heated leather seats on ?
Anyone ???

 

[pauldazzle]

Coolant Sensor off ebay

 

[Johnjones]

Do you think that might be causing trouble Paul? Should i get the gsf one for £17

 

[Johnjones]

My father's B5 currently has the heated seats on all the time and he's still averaging 51 mpg and that's mainly running around the villages, so I guess it has little affect.

How much fuel economy do you think you loose with keeping heated leather seats on ?
Anyone ???

 

[stu_m]

its best to replace with OE all the time if you can

But Im'm not sure you have a problem at all

 

[Johnjones]

Thanks Stu, it's just my brother has a 115 pd and gets 55 on motorway at 70....i was hoping for similar. Does OE mean it's genuine audi part or is it just the equivalent? Thanks again

 

[stu_m]

is his the B6 or the B7? and is that worked out off the DIS?

My brother has a B7 2.0tdi and his DIS shows 55mpg average but he doesnt get that if worked out tank to tank he gets roughly the same as me 44-48 average

OE means original equipment so audi parts the actual term is OEM (original equipment manufacturer) but every leaves the M off

If you think you have a problem get it scanned for codes and the MAF checked too check the VCDS map for a user near you. What is your location? I'm in Hull and have VCDS if I can help

 

[Johnjones]

His is the B5 with the 115 pd engine and it was calculated by brimming the tank. I had it scanned and no codes came up except for an unidentified Ecu and aircon codes. There's no compressor in it hence those aircon codes. I'm in Bristol. Is the Maf easy to check? Thanks again.

 

[Greeny233]

My 1.9tdi sport Quattro Avant does 47mpg on a long run sat at 70-80mph if I want over 50mpg I have to slow down to 60mph. 47mpg is good for such a big heavy-ish car. You could always fit a 90bhp A4 B5 engine, my old B5 used to do 50mpg everywhere and 60+mpg on the motorway.

 

[AudidriverA4]

My 1.9tdi sport Quattro Avant does 47mpg on a long run sat at 70-80mph if I want over 50mpg I have to slow down to 60mph. 47mpg is good for such a big heavy-ish car. You could always fit a 90bhp A4 B5 engine, my old B5 used to do 50mpg everywhere and 60+mpg on the motorway.

That's excellent fuel economy, there has to be something wrong with my FWD 1.9 tdi 130 bhp because I'm only getting around 40 mpg

Although my car is driving perfectly and no warning lights on dash

 

[Greeny233]

Mine has been remapped, but I doubt that would make much difference, the biggest effect on economy is the driver. Even a Prius has to be driven economically otherwise it will only do mid 30's mpg.
I always use Shell V Power diesel in mine rather than cheap supermarket fuel and that makes a noticeable difference. You could try some fuel system cleaner and change the fuel filter. There are lots of little things which will help with fuel economy.