Does anyone know the quoted optimum speed in 5th gear or the rpm per gear to achieve maximum mpg. Mainly interested in the former so as to set the cruise control on long journeys. (Conditions allowing)

^{2000rpm - based on personal experience rather than a "quoted" figure.}

I found a BSFC plot for the 1.6tdi in a research paper which was not officially supplied but created by the researcher. It is attached below.

surely all you have to do is find the speed at which the trip reads the highest instant mpg, and just stay there, OK, a bit of adjustment, but its not hard to find.

50mph in 6th in mine.

Best fuel consumption is obtained by burn and cruise (ie no throttle) rather than fixed cruising speeds plus other techniques hyper-milers use.

http://www.hypermiler.co.uk/

Have got 600 miles from the TSI VRS and 650 miles from the 1.8 TSI DSG and Fabia VRS is getting up to 450 miles now but only has 6K on the clock and these are not hannging about ie averaging 70/75 mph on the computer.

Edited 9 September, 201213 yr by lol

per a post above,

try and keep her as near at 2000rpm as possible and probably not exceeding 60mph with gentle acceleration and braking.

I think the transmission rarely exceeds 2500rpm before changing up and dropping back to 1500rpm or so, but settles at about 2000rpm even if travelling at 30 or 40 mph, simply keeps down the gears to hold the optimum most efficient revs.

from a non scientific study of the dsg equipped 1.6 TDI over 34,000 miles

VW boffins have thus concluded.

Best fuel consumption is obtained by burn and cruise (ie no throttle) rather than fixed cruising speeds plus other techniques hyper-milers use.

http://www.hypermiler.co.uk/

Have got 600 miles from the TSI VRS and 650 miles from the 1.8 TSI DSG and Fabia VRS is getting up to 450 miles now but only has 6K on the clock and these are not hannging about ie averaging 70/75 mph on the computer.

I struggle to get 600 miles to tank out of my 140 tdi so to get better economy out of a 1.8 tsi is great, at that economy why to people bother with diesel.

Pulse and glide techniques are far more effective on a petrol than diesel. This is due to the pumping losses from the throttle plate in a petrol engine.

For some reason I can't quote anything on this site anymore.

After running a Subaru Impreza for 10 years any speed is the Optimum Speed for Maximum MPG. When you only got 20 mpg on a good run or a bad run, no difference, it just would not do economical whilst the engine was running. So now everything is a Bonus.

I would imagine that its just below where the turbo kicks in.

I've found the best economy is around 2,250rpm... Although, this is the vRS TDI 6M.

Kind of awkward, though. 2,250rpm at 100km/h is 5th gear.

4L/100km highway doesn't dispute, however! (70mpg IMP)

I struggle to get 600 miles to tank out of my 140 tdi so to get better economy out of a 1.8 tsi is great, at that economy why to people bother with diesel.

The 1.8 TSI, especially with DSG, is something very special, and I own both petrol VRSs.

Doing mostly long journeys ie 100 miles plus helps get good average consumptions plus picking tall vehicles who are doing the 75/80 and sitting 30/40 metres back in their slip stream and other hyper-mileing techniques. Tend to use Michelins which even the Sports tyres are good on fuel.

VW-Audi have load of tricks in the pipeline and have 60 mpg plus petrol cars which still have sparkling accleeration though they tend to be in the Audi brand rather than the Skoda brand.

Cars will be mostly petrol hybrid over the next 5 to 10 years with hybrid systems as powerful as the engine. Prototype racing technology, particularly the engine powering one pair of wheels, probably rear, and the electric dealing with the front for regenerative brakes and extra power looks the way to go.

Peugeot's move to diesel hybrid looks to have failed, just too expensive, and PSA has now been removed from the CAC 40 as they are having such a bad time.

Edited 9 September, 201213 yr by lol

May I apologise for my erronous posting above, perhaps a Senior Moment overcame me?, but my comments actually referred to wor daughters diesel Totota Yaris, which I have mostly been driving recently, as her nibs broke her leg and is being chauffered by Senior Managment in der DSG Octavia.

So anyway on the way back from Portrush this evening the transmission was choosing to hold 7th uphill past the caravan park towards the Royal Court...................at about 1200rpm, only dropping to 5th, when I started to accelerate just about the Royal Court, then dropping back to min revs in 7th once over the hill.

Which is to say drive her like the old 1998 1.9 trick turbo TDI , keep the gears up and the revs down and use the torque,

I imagine not exceeding 60 or 65 would be prudent for max fuel economy.

cheers

marcus

Peugeot's move to diesel hybrid looks to have failed, just too expensive, and PSA has now been removed from the CAC 40 as they are having such a bad time.

I actually liked the idea of the diesel hybrid as it also offered 4wd on demand. The biggest problem from the reviews i read was that the auto gearbox was hideous. Think it was an automated manual with a single clutch. Yuk.

Its probably true though that this combination is too expensive but would probably make more sense in a large SUV.

On topic though, i always thought 56mph was the optimum speed for best MPG as this used to be what the claimed MPG figures were based on. Bit of a blast from the past as its all about combined figures now. Was this why 56mph was used or was it for another reason?? Seems a strange speed otherwise.

Well its a difficult multi-variable problem to find the optimum. I have a 1.9 tdi which produces about the same power as the new 1.6 Cr diesel.

Obviously the slower you drive (within limits) the better fuel consumption - but one has to be practical. I found recently that on my 1.9 TDi (105 bhp) on a trip to Scotland, that on the motorway, I got good economy by setting the cruise to 2500 rpm, as a good compromise.

Above 2500 rpm it is "trying harder" whereas @ 2500 rpm it is "on song" ish. 2500 rpm on mine gives 75 mph indicated. Its tempting to push to 80 mph, but the rpm is then pushing a bit harder against the square law air resistance.

My intuition suggests between 60 and 75 mph on highways to get the best mpg v "c'mon get on with it". I got over 50 mpg but no where near 60 mpg which some claim.

I'm satisfied with 50 mpg.

n topic though, i always thought 56mph was the optimum speed for best MPG as this used to be what the claimed MPG figures were based on. Bit of a blast from the past as its all about combined figures now. Was this why 56mph was used or was it for another reason?? Seems a strange speed otherwise.

'Sfunny, but my other chariot is a Polo 1.4 TDI which at 2000rpm is exactly 56mph. On a 50 mile commute I can squeeze >75mpg on a dry road with no headwind. 'Bluemotion'? Who neeeds it...

I tend to keep the Octy @2000rpm in 6th on a long haul, provided time isn't of the essence, and it'll give >50mpg at 65mph, which ain't bad for a 4x4.

back from an 800 mile round trip to England and back, over the 150 odd miles to Carlisle ex NI via Cairnrayn an indicated 67.5mpg at 50 odd mph.

then the rest of the journey at motorway speeds or stuck in traffic.

Overall 58.9mpg at 49mph, as there was horrondus congestion on the M6 ret journey

so at sensible motorway speeds an genunine 60plus mpg should be entirely possible ......................for longer runs.

I would like to achieve an indicated 60mpg at an indicated 50 mph, I will get there yet as her now nicely loosened up at 35,000 miles.

Edited 16 September, 201213 yr by dieseldogg