Poor MPG after 20k...

[AndyVTR]

Had my 20k service about 3 weeks back.

Since then I've not been able to get the 600 miles I need out of a tank.

Admittedly 2 of the weeks I only needed 4 days worth of fuel so I was a bit less frugal with it.

This week though I've tried and my trip 2 (which I reset when filling up) was showing 50.3mpg. Managed 546.4 out of it and the range was showing 25-30 left.

Could it be:

1) Me.
B) The cold weather.
iii) My ECU learning my driving style after they've reset it???

Answers on a postcard gents.

 

[the cat]

Had my 20k service about 3 weeks back.

This week though I've tried and my trip 2 (which I reset when filling up) was showing 50.3mpg. Managed 546.4 out of it and the range was showing 25-30 left.

Could it be:

1) Me.
B) The cold weather.
iii) My ECU learning my driving style after they've reset it???

Answers on a postcard gents.

OR

d) you didnt fill the tank up full. In other words, (1), you.

Certainly dont think its anything to worry about - only getting 40 mpg at present although she's still brand new...

 

[JBS Sales]

Or it could be that the price of fuel has gone up quite a bit over the past wek or so.
It could also be worth checking out the temp sensor.
I.E it could be thinking that the engine is still cold when it is warm so running a bit rich still.
Sarah

 

[AndyVTR]

d) isn't an option. I brim it every weekend otherwise I can't get a full week out of it.

I'm used to 50+mpg but that all depends on driving style etc.

Price is nothing to do with it either if it's filled every time.

 

[Craig Senior]

I'm struggling to get 400 miles from a tank.

Even 2 100 mile motorway trips have only increased it to 440 miles.

I know stop/start town driving isn't good for mpg but it is starting to annoy me. My motorway trip only acheived 49mpg average.

Maybe I need another big motorway roadtrip to get the average up.

 

[sssstew]

Had my 20k service about 3 weeks back.

Since then I've not been able to get the 600 miles I need out of a tank.

Admittedly 2 of the weeks I only needed 4 days worth of fuel so I was a bit less frugal with it.

This week though I've tried and my trip 2 (which I reset when filling up) was showing 50.3mpg. Managed 546.4 out of it and the range was showing 25-30 left.

Could it be:

1) Me.
B) The cold weather.
iii) My ECU learning my driving style after they've reset it???

Answers on a postcard gents.

a combination of all 3 i would say. give it some time and for temp and weather changes then see.

 

[cheshire cat]

do a ventectomy

 

[AndyVTR]

Will give it a couple more weeks of trying then... costing me a fortune.

I usually vent it for a bit too.

 

[prc]

Most likely down to the cold temps around. I was also surprised that my mpg would go down during rainy weather (due to the extra traffic).

 

[AndyVTR]

Aye I've noticed the traffic can really mess with my indicated MPG before.

Bring on warmer weather!

 

[craig-pd130]

Problem is, factors like cold weather and traffic can make a 5% or greater difference to fuel consumption. In a petrol car, this is 1.5 to 2mpg so you don't notice. In a diesel, it's 3 / 4 / 5 mpg so you start thinking something's wrong ...

 

[prc]

Could also be the temp sensor on it's way out. Forgot to mention that mine is. Takes about 8-9km just to start moving, and about 20km to reach 90ºC. A cold engine will use much more fuel.

 

[micky 32]

Could also be the temp sensor on it's way out. Forgot to mention that mine is. Takes about 8-9km just to start moving, and about 20km to reach 90ºC. A cold engine will use much more fuel.

Would a thermostat not have the same symptoms?

 

[prc]

Would a thermostat not have the same symptoms?

Yeah, but in my case, even though the temp reading hasn't moved, after about 3km I start getting hot ar from the heater, which would indicate that the motor is actually heating (even though the temp sensor hasn't moved a mm).

 

[AndyVTR]

Doubt it's the sensor as it's only 6 months old.....

Anyway, it's back. Averaged 5 degrees and 53mpg this morning!

 

[deezal]

I usually get 54 -6 mpg on average at this time of year, in the summer it rises to 60 but I do a fair bit of town driving/short journeys. But on long journeys like yesterday, I did 170 motorway miles at a steady 55-60 , brimmed the tank before and after and it used 10.4 litres -works out at 74mpg. On BP Ultimate.

 

[AndyVTR]

170 miles I can believe it. More accurate over a full tank though.

 

[raymondbreen]

I average mid 40's, cruising along on the motorways. Had some fuel additive put in the other week, and it has made a noticable improvement to the low level accelaration, also the economy has increased slightly

 

[AndyVTR]

Mine is miles better this week with the temperature averaging about 7 degrees.

 

[prc]

Pretty much granny driving last week

1ST TANKFULL
1023km with 53.65L
2ND TANKFULL
984km with 48.78L