[spiTTfire]

Is there an optimum point in the rev range where my GT Tdi is running at its most economical? I've always been led to believe that you should change up gear as soon as possible. Though looking at the fuel computer this isnt the case.Sometimes im getting more MPG in 5th at 65-70 than if I was in 6th gear at the same speed.

Any thoughts?

Just had to fill her upfor the first time from new.512 miles out of a tank, and the dealer said the MPG would be poor whilst the engine was brand new.

 

[JMcQueen]

Thats not too bad. I get about 450 out of a tank before the warning light pings in to tell me to refuel and mines got 11K on it. I know what you mean about the gears though. Ive found its a bit hit and miss i.e sometimes its best to have it at about 2500 revs to keep the turbo spinning, other times I can sit in sixth gear at 60 and get about 65mpg!!!

My fuel economy just nose dives after 70mph. Its like VW built in a speed limiter by stealth - dont go faster than 70 or it'll cost you!.

 

[SteveTDCi]

Peak Torque is at 2000rpm so I'd change at around 2200. Peak Power is produced at 3500 (well on mine it is) so there is very little point in reving past this. I just fill mine up and don't bother with the MPG

 

[Richy777]

I can get 600 miles before the fuel light on my 1.9tdi, I pref. to keep it between 1800 & 2400 rpm I had a 130 tdi mk4 and found that 6th gear below 1800 rpm to use more fuel than 5th.

just for the record I have had 642 miles out of one tank, my car is now 8 weeks old and is starting to get better fuel returns with 6000 miles on it now.

 

[kenl]

just for the record I have had 642 miles out of one tank, my car is now 8 weeks old and is starting to get better fuel returns with 6000 miles on it now.

Very impressive.

What mpg are you averaging, >50mpg?

 

[sammyboy]

I remember reading an article that said brisk acceleration was actually more economic all round whatever the car, not red lining it, of course.

 

[tylerama]

Christ almighty.. I am SO getting a dirty derver for my next car.. fule consumption like that is too good to ignore !

 

[Spin 150PD]

Most I've ever got out of the 2.0tdi was 550 miles and this was on a long run averaging 80/85mph.  The beauty of the 2.0tdi is even on relatively short journeys with absolutely no thought of driving economically I still average 42mpg and this is with my car remapped to 180+ bhp.  The fuel eceonomy does get better with miles as does the performance,  enjoy

 

[A7_UFO]

I could drive at 130mph in my old PD 130 and it returned a better mpg than my mk3 GTi 8v at 70mph.

 

[Spin 150PD]

Diesels - you gotta love em

 

[Benn130TDI]

According to stock figures, peak torque in my PD130 is supposed to be at 1900rpm. 70-75 in 6th is at about 20000 - 2300 it depends on if you're going uphill/downhill or on level ground.

As a general rule of thumb, I leave it in 5th up to 70, or if it's one of those times when the traffic is going from 60-70 all the time. Tend to go into 6th if I'm staying at 70-75 (or 80...) as the revs are lower and get better mpg on the trip computer.

 

[ct.p]

In theory the most economical engine speed is where you get peek torque.

Going through the gears it can vary enormously.

The best possible would you believe is 4th gear at about 30, over that and you start having to factor in wind resistance.

Thing is, who can stand going 30 if they can help it?

On the motorway, try going 60 with cruise on in 6th, that's about the best compromise, in my PD115, I can easily average 60 to 65mpg over a 30+ mile run at 60.

Do it at 70 then 80 then 90 etc and you will notice dramatic drops in mpg, at 90 and accelerating hard to get there in traffic, I'm lucky to get more than 40-43mpg, in fact high 30's if I loon it.

Accelerate as gently as possible, that is the key to saving fuel, I know, I've tried every way possible and am really obsessive about it. Funny though on the way to work I usually granny it and do my most cunning and clever mpg experiments but on the way home I couldn't give a monkies and normally try go as fast as the millenium falcon.

Of course the MK5 2.0 TDI might be a wonder engine where all the laws of physics have been turned on their head? I can't see it being as torquey as a 1.9 8v at low revs but reckon it would be a dream in the mid to high revs range.

 

[SteveTDCi]

Rather than insert the pictures I'll leave the links in. I'll take some better images of the actual plots but the one that rises is the power, and the one that starts high and tails off is the torque graph.

http://img.photobucket.com/albums/v11/stevetdci/2005_0727Image0161.jpg

http://img.photobucket.com/albums/v11/stevetdci/2005_0727Image0160.jpg

http://img.photobucket.com/albums/v11/stevetdci/2005_0727Image0159.jpg

 

[Giblets]

At a guess, 56mph, as this is where all the official mpg figures that all the manufacturers and magazines take it from, as a consequence that is where all the gears are optimised for

 

[kenl]

At a guess, 56mph, as this is where all the official mpg figures that all the manufacturers and magazines take it from, as a consequence that is where all the gears are optimised for

I don't think that is how it is measured anymore.

 

[talk-torque]

Thing is, it's not just about the revs. Diesel consumption is hypercritical to throttle setting or, more accurately, fueling, so if gradient/wind or whatever, means that a given speed can be maintained in a lower gear/at higher revs with lower fueling, then this will give better economy. I don't think there's a magic rule for knowing when, though - Suppose it might come with experience of the engine note etc. HTMS

 

[Irish]

If I see 400 miles out of a tank I feel special.

 

[Spin 150PD]

Of course the MK5 2.0 TDI might be a wonder engine where all the laws of physics have been turned on their head? I can't see it being as torquey as a 1.9 8v at low revs but reckon it would be a dream in the mid to high revs range.

My 2.0tdi produces more torque (remapped) than my old PD150 but doesnt feel like it as the delivery is now more evenly spread - just my opinion but I preferred the kick in the back, neck jerk of the 1.9PD. MPG wise my remapped 150PD also returned greater fuel economy, not a lot probably an average of plus 3mpg, but on a long run it was even more.

I'm not knocking the 2.0tdi as it is superb just highlighting the differences, the 2.0tdi is more refined with a smoother power delivery, the 1.9 8V - a bit more fun

 

[Milkfloat]

You bunch of old men.......  I read an article by some Dutch scientists who worked out that the Taxi Driver school of driving is best.  They suggest that you floor the car to 2k revs then change.  Gentle acceleration does not work it shoud be everything you have got.  No idea if it is true, when you have a relatively expensive car the depreciation will hit you a lot more than 1 or 2 mpg.  i generally don't care about mpg too much.