Poor Diesel Economy

[Guest blatters]

Presumably an auto box makes quite a difference. But I'm agog at all these stories of 50mpg from a 115 - I struggle to get 40mpg on long journeys of congested motorway driving at about 60-70mph.

 

I would think the manual box is best for fuel economy.

 

The 50mpg+ is true for the TDi 115bhp. I'm basing this on the trip computer as I can't be bothered to do the manual calculation based on fill-up to fill-up. Example, we travel down the M6 from Scotland in the late evening arriving in North Kent at midnight. The journey is 420 miles and the trip computer says that the Galaxy manages 51mpg or so. This is at 70mph mainly on cruise control. I've been caught by the mobile speed camara that Cumbria places on the motorway bridges in the vans with their sliding side doors open. 3pts does not result in higher insurance premiums for a speeding offence but another 3pts will, so I'm being careful and the cruise control stops the heavy foot syndrome kicking in on the throttle.

 

Now if it were Friday night on the M6/M5 junction at around 6pm that would be another matter but you'd be mad to even go there then, eh?

 

........Blatters

[rwtomkins]

Yes, sorry to be unclear, I meant the auto box would lop quite a bit off the mpg - they always do, don't they? Not least because IIRC they've got one gear less than the manual box.

[Ivor_E_Tower]

3pts does not result in higher insurance premiums for a speeding offence but another 3pts will, so ....

Depends on your insurance company. Some (many) now DO penalise even for 3 points.

 

..and RWTomkins - it's not just the number of gears that affects mpg, it is the gear ratio (eg how many mph per 1000 rpm the car does in top gear). The TDI 6-speeders are set to run at about 32mph per 1000 rpm in 6th, so just over 2000rpm to get 70 mph. This aids refinement as well as mpg!

[GSMGuy]

My auto is about 30mph/'000 so @ 70 it's 2500rpm, not much difference there - but you have to take into account converter slip/loss and the fact that auto's accelerate differently due to this - ie they sustain a higher initial revs and the transmission/converter speeds the car up to match.

 

 

 

Mike

[MrT]

Why worry about slight differences in MPG unless you are a high mileage user?

 

The difference between a 50mpg and 40mpg is less than

[Richmond]

I have a V6 so the expression 'fuel economy' has no meaning for me. The Galaxy is the first car I've had with a trip computer and I notice that fuel consumption is very dependent indeed on speed. On the m'way at a steady low 80s mph, it's OK, high 20s mpg ish. Above 85 mph, it plummets to low 20s mpg ish; at that point I switch the display to 'average speed'. I wonder if the large discrepancies between reported mpgs of all you consumption conscious diesel drivers are due in part to fairly small differences in driving styles.

[Masked Marauder]

I wonder if the large discrepancies between reported mpgs of all you consumption conscious diesel drivers are due in part to fairly small differences in driving styles.

I drive Volvo trucks for a living. My partner is a dental nurse.

 

I have been trained by Volvo to drive engines with variable vane turbochargers, my partner has not.

 

I get an average of about 45 mpg, she gets about 35.

 

Things to be carefull of are too early change downs and too late change ups. Always use the highest gear possible, all the torque is low down. Don't change down through the box when slowing down, leave it in the higher gear until you need to change down two or three gears. Harsh acceleration is not needed, the throttle position, engine revs, load, airflow etc are all detected by the ECU and the turbo vanes and fuel is then set for best torque for the job.

[Denis]

Worth pointing out that Continental claim that their 'Ecosaver' tyres give a 10% improvement in fuel economy. I can get 28mpg on a steady 70mph motorway run, rather less when I'm on the open road and give the lady a chance to growl! http://freeforums.bizhat.com/html/emoticons/naughty.gif

[Ivor_E_Tower]

I drive Volvo trucks for a living. My partner is a dental nurse.

 

I have been trained by Volvo to drive engines with variable vane turbochargers, my partner has not.

Wow - do they train dental nurses to drive trucks these days?

:lol:

[Masked Marauder]

They should do, she has nothing else to do since the practice went to private patients only.

[GSMGuy]

Worth pointing out that Continental claim that their 'Ecosaver' tyres give a 10% improvement in fuel economy. I can get 28mpg on a steady 70mph motorway run, rather less when I'm on the open road and give the lady a chance to growl! http://freeforums.bizhat.com/html/emoticons/naughty.gif

Bet they give a 10% loss of grip too!

 

:lol:

 

Mike

[Denis]

Worth pointing out that Continental claim that their 'Ecosaver' tyres give a 10% improvement in fuel economy. I can get 28mpg on a steady 70mph motorway run, rather less when I'm on the open road and give the lady a chance to growl! http://freeforums.bizhat.com/html/emoticons/naughty.gif

Bet they give a 10% loss of grip too!

 

:lol:

 

Mike

Well... I don't know, my 'other car' is a bike and I use Conti tyres on that as well. They use the same technology as the car tyres- Silica rubber, they roll better and grip better at the same time. The bike tyres wear a lot quicker but I have found the car tyres last quite well, similar to the Dunlop 2020's I used to use, about 10k on the front.

[seatkid]

IIRC Continental claimed between 3 and 5% improvement , but now that claim is missing from their literature, probably because it is difficult to prove and the competion have probably caught up with their own ECO models.

 

Great tyres nevertheless, BTW Uniroyals are also made by Continental.

[Richmond]

Worth pointing out that Continental claim that their 'Ecosaver' tyres give a 10% improvement in fuel economy. I can get 28mpg on a steady 70mph motorway run, rather less when I'm on the open road and give the lady a chance to growl! http://freeforums.bizhat.com/html/emoticons/naughty.gif

Bet they give a 10% loss of grip too!

 

:(

 

Mike

Interesting thought. Would the easiest way to achieve better fuel con and reduce tyre wear be to make the tyres less grippy? Sounds possible. With traction control, ABS and so on, who needs grippy tyres anyway? :lol: Craaaaaasssshhhh

[GSMGuy]

Back onto the topic... Lol - Have now covered 240 miles mainly in town and the gauge is not yet down to half...

 

Mike

[seatkid]

Almost "brimmed" my tank (probably could still manage another 4 or 5 litres though) I've done 140 miles and the gauge still hasn't moved off the full end stop.

 

With the MAF on the way out (I think) averaged 46.3 mpg over the last 1400 miles at an average speed of 39mph, mixed driving,Sainsbury diesel.Longest I've gone on a tank is about 720 miles, but don't let the tank go down too low nowadays as I fill up at the rumour of a price rise (every other week).

 

I'm never in a hurry though. I'm the guy everyone swears at, as I don't feel the need to travel at speed limit+20% until the last possible moment then brake like f**k, only to smoke the tyres to get away again. Let em wait - if someone behind really annoys me I go out of my way to slow him down further and when he eventually risks all to get past, I put my foot down and let him sweat :( :( :lol:

[johnb80]

if someone behind really annoys me I go out of my way to slow him down further and when he eventually risks all to get past, I put my foot down and let him sweat B) B) B)

You're a very, very, naughty boy..... I suppose you'll be moving on to towing a 26' caravan next to really annoy other drivers :lol:

[Richmond]

Let em wait - if someone behind really annoys me I go out of my way to slow him down further and when he eventually risks all to get past, I put my foot down and let him sweat :lol: B) B)

It is reassuring to know that there are public spirited chaps like you out there who know how we should all be driving and go out of your way to ensure that we live up to your standards.

[Guest jus]

managed 9 mpg the other day- horrendous traffic, 2 miles in 1 hour