MG-Rover.org Forums banner

Miles per gallon ?

10K views 41 replies 26 participants last post by  Steve Mac 
#1 ·
My Rover 75 is an 2004 model cdti 131 AUTOMATIC estate car an the economy round town is dreadful, goingto my office in central London (traffic) I get about 19mpg ,my previous car a Volvo 3litre 24 valve estate managed 16.8 mpg!so 19 mpg diesel is not great . The faster I go on a motorway it seems the economy improves and I get about 35 mpg . It never ever averages over 40 mpg whatever I do .Does not leak and no black smoke ,new map sensor might have put up the mpg by a fraction but not much answers on a postcard please ! David Munson
 
#3 ·
I have a similar car, although a cdt, not the 'i'. The fuel consumption does vary a lot. Its the town traffic that does it. On motorways, according to the display, at 60 - 70 it shows about 45mg or higher, (that is setting the display at that speed and not counting accelerating up to it etc). I have just done about 240 miles, mainly A roads and dual carriagways, and about 20 miles round town (but not central London) and my dash display is showing 37.9mpg.
On long motorway runs I have had it average over 40mpg. It think it depends when you reset the display the period it calculates over.
 
#4 ·
mechanic said:
My Rover 75 is an 2004 model cdti 131 AUTOMATIC estate car an the economy round town is dreadful, goingto my office in central London (traffic) I get about 19mpg ,my previous car a Volvo 3litre 24 valve estate managed 16.8 mpg!so 19 mpg diesel is not great . The faster I go on a motorway it seems the economy improves and I get about 35 mpg . It never ever averages over 40 mpg whatever I do .Does not leak and no black smoke ,new map sensor might have put up the mpg by a fraction but not much answers on a postcard please ! David Munson
Wow! I'm managing to average not far off that with the 4.6L V8 in my ZT-T 260! That can't be normal.. I assume you have tried calculating it manually on a fill up to make sure it's not some sort of problem on the trip computer?
 
#5 ·
I have just filled up after 240 miles in mine, first time in ages. Most of journey has been to and from work, 3 miles in total. My average was 24 with an average speed of 18 mph. I always have the air con on auto so that wont help. I have just driven 12 mile since fill up and its average is 36mpg. On a 700 mile run last year I averaged 44 mpg and I wasnt hanging about. Looks like on short cold journeys it just eats the bloody stuff!!!!
 
#8 · (Edited)
I have the ZT equivalent, a ZT CDTi 135 + Auto, and up until the crash, I was averaging 31.76mpg. This is an average since i bought the car just over a year ago. Most of my journeys are around town or on single carriageway A roads.

The best I have ever had was 40.66mpg and the worst 26.34mpg.

It sounds as though something is amiss.

By the way, these are actual figures calculated from miles & litres. And I also the tuning box fitted resulting in around 150-160bhp.
 
#12 ·
I have a CDTi Auto too and the worst I have seen is around 21 mpg from lots of 2 mile journeys to and from work on a cold engine with lots of traffic lights.

I have noticed that I get a better mpg if I drive a little more like a BMW owner, ie. a bit more enthusiastically.

Now that the weather is a little warmer I seem to be averaging around 26 mpg on the same route to and from work.

On my run down to Hampshire next week I am expecting aroung 45 mpg.

As I have said before I see no reason to replace my 75 with another CDTi, I shall instead return to a V6 motor, although it will have to be another auto.
 
#13 ·
paulmariner said:
I've got a 2002 cdt auto with 123,000 on clock.
I've travelled 2,930 miles since picking the car up, mixture of roads and some long, some short journeys.
Average mpg (actually miles v. litres of fuel put in) is 44.

I'm happy with that!

I agree. I have the same car and get the same mpg although on really long runs slighlty more.
 
#14 ·
OK, a few things to check!

1. Check the air filter is clean - this has a big effect and the 30k service interval is too long.

2. Switch the air con OFF (ECON), this makes 2 or 3 MPG difference.

3. Change oil to MOBIL 1 - this helps.

4. Make sure the MAF is working correctly.

5. Check the EGR valve is clean.

6. Check the tyre pressures are correct.

7. Use BP or Shell fuel - NOT Supermarket stuff.

8. Use Millers Pro Plus diesel additive in your fuel.

9. Try not to do short trips!!!!!


All of these tips will help improve the MPG. I average 41-43MPG in my CDTi with 160BHP and have seen 46+. The worst ever is 37.
 
#16 ·
Mpg

My 75 CDTi Tourer Auto averages around 38 MPG (based on fill ups). I normally have it on cruise at 75/80 MPH and probably 80% of my mileage is motorway.
On the computer, consumption seems not to vary much whether at 70,80 or 90 MPH ! I would like the better consumption of a manual but will never tire of the effortless driving my auto gives me.

By the way, I think auto drivers ought to be allowed to have a sandwhich when driving 'cuz they don't have to take their hand off the wheel ! ! ! Can we have a vote ! ! !
 
#18 ·
crofts said:
My 75 CDTi Tourer Auto averages around 38 MPG (based on fill ups). I normally have it on cruise at 75/80 MPH and probably 80% of my mileage is motorway.
On the computer, consumption seems not to vary much whether at 70,80 or 90 MPH ! I would like the better consumption of a manual but will never tire of the effortless driving my auto gives me.

By the way, I think auto drivers ought to be allowed to have a sandwhich when driving 'cuz they don't have to take their hand off the wheel ! ! ! Can we have a vote ! ! !
A sandwich?
With an auto box and cruise control, I think a nap would be more appropriate for me.
Ron
 
#19 ·
That does sound low. My 1.8T Tourer manual averages 26 mpg around town (ave speed 18 mph) and I've have just done a 100+ mile motorway run, ave speed 55, fully laden and got 39.2 mpg! The best thing I've found to improve my fuel consumption is to drive about with three babies in the back! (Not very practical I know, but you're welcome to borrow my three to see if it works)
 
#20 ·
iga said:
That does sound low. My 1.8T Tourer manual averages 26 mpg around town (ave speed 18 mph) and I've have just done a 100+ mile motorway run, ave speed 55, fully laden and got 39.2 mpg! The best thing I've found to improve my fuel consumption is to drive about with three babies in the back! (Not very practical I know, but you're welcome to borrow my three to see if it works)
Three babies !!?
Blimey, I imagine MPG is the last of your worries at the moment anyway!
Good luck.
 
#21 ·
mechanic said:
My Rover 75 is an 2004 model cdti 131 AUTOMATIC estate car an the economy round town is dreadful, goingto my office in central London (traffic) I get about 19mpg ,my previous car a Volvo 3litre 24 valve estate managed 16.8 mpg!so 19 mpg diesel is not great . The faster I go on a motorway it seems the economy improves and I get about 35 mpg . It never ever averages over 40 mpg whatever I do .Does not leak and no black smoke ,new map sensor might have put up the mpg by a fraction but not much answers on a postcard please ! David Munson
I have a 2005 cdti AUTO and driving 100 miles a day to and from work across the fens and a bit in Cambridge I get between 42 and 44 on the computer.
My friend has an identical car and does a bit more on dc's and he gets around the same. Pretty poor realy but the thing is built like a tank.
You could try driving it in sports mode as some say this helps a bit

Barry
 
#24 ·
pshuttle said:
I have a 2000 CDT - Most I ever get is just under 40. I do have a digital tuning box fitted though and at present my MAF is unplugged...

Pete
Leaving the maf unplugged is not recommended.

Apart from the lack of air flow signal, you now have no air temp sensor either.
So the ecu defaults to -5C and this will tend to over fuel the engine, especially at low rpm and in warm weather.

You also lose the over run fuel cut off which again, will affect fuel consumption and the IAT signal is also used to adjust the timing, so this will not be optimum as well.

Ron
 
#25 ·
Hey,

I know it is not recommended - but I have yet to have had a major problem. I have spoken to one guy who has run it for 30k without problems but he may just have been lucky.

It runs less rough than when I plug the knackered MAF in. You will be pleased to know I will be looking to buy a full synergy kit from you Ron come August. I have a digital tuning box already but would prefer your customisable solution!

Look forward to using a Pierberg MAF too.

Pete
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top