50mpg from 1.4TDI90 on long trip - normal?

froggy said:
“2200rpm at 60mph” that’s good to know, my engine runs exactly at this, so after all its been through?? it’s doing well! I read earlier in the thread about tips on economy and found sticking behind a HGV (not too closely!) certainly made a difference ??
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Martin got the DIS to read over 82mpg over 150mile trip on our 75bhp by doing this but I think life is too short do it ?
 
Proghound said:
If you ask me, it's at peak torque, that way the engine can handle the variations of the road with a minimum of extra throttle. On a standard TDI75 the peak is 2200revs which equals 60mph - so 55-65mph is perfect. The figures on a 90 will probably be different - with a VNT turbo I expect a wider rev range where it produces over 90% of peak torque, on the 75 it's a bit of a spike around that 2200 mark.
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On a 90 I find around 45mph the most economical, when you get past 60mph the mpg starts to drop off fast. I’ve done 79.5mpg to a tank by hyper milling. But it normally gets 65mpg to the tank this drops off the colder it gets.


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On my 90 had to do round trip to Heathrow airport (mostly using M25), set cruise to 60 MPH, (running RS4 17' on cheap tyres Rotella) and averaged around 71.7 mpg on the DIS for the 65mile trip, with faulty thermostat, (temperature barely above 60°C).

However, when I replaced this with low cost Circoli thermostat from well known parts store, the temperature stayed rock steady at 90°C, same route with similar cruise control set to 60 MPH outside with temperature at 11°C the car averaged 81.4mpg off the DIS for the same 65miles trip. Could not he happier!

Agree with Edwrai on full tank 50:50 mix of road and motorway can easily achieved 65mpg+. Before the thermostat fix I could barely manage an average combined higher than 50mpg. So important to make sure the thermostat is working properly or else I understand the car's computer is constantly instructing more diesel injection into the engine to help increase the water temperature up to 90°C.
 

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@froggy - @Azim's recent post on his 40mpg TDI90 made me look at this again, how are you getting on with improving your car's fuel consumption figures? With diesel now at £1.85/l in some places round here, this has never been such a relevant thread!
 
dj_efk said:
@froggy - @Azim's recent post on his 40mpg TDI90 made me look at this again, how are you getting on with improving your car's fuel consumption figures? With diesel now at £1.85/l in some places round here, this has never been such a relevant thread!
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I have been thinking the exact same thing as have many people I suspect. Quite lucky ‘oop north as we can still get diesel for £1.64. I’ve just filled up from near empty at a cost of £61.56. I will report back in due course, but after 10 miles easily achieved + 60mpg (with a fair bit of in gear coasting) - before, with the 17” sports alloys and ruined suspension, getting 60mpg was impossible. This is however based on just 10 miles, so fingers crossed the new 15” basic alloys and suspension continue to make a huge difference!
 
froggy said:
I have been thinking the exact same thing as have many people I suspect. Quite lucky ‘oop north as we can still get diesel for £1.64. I’ve just filled up from near empty at a cost of £61.56. I will report back in due course, but after 10 miles easily achieved + 60mpg (with a fair bit of in gear coasting) - before, with the 17” sports alloys and ruined suspension, getting 60mpg was impossible. This is however based on just 10 miles, so fingers crossed the new 15” basic alloys and suspension continue to make a huge difference!
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58 in my ATL with winter tyres on pepperpots at moment.
 
I’ve had a nightmare with the map sensor on mine, switched out and I’m seeing better fuel consumption…I don’t know how much by yet, but I used to struggle to get 400 miles in a tank but I’m already on 110 and not a quarter used.

I think you can test your map sensor with a vac gauge and check the voltages. Someone smarter than me can explain or link. :)

Also we had £1.98/litre standard diesel near us ?
 
don't forget....domestic electric has gone up 30-50%....think of the charging for those?
And the range will only get less with battery age...
 
Hi,
I think if you use better fuel, your mpg will increase.
I have outlander PHEV and drive with supermarket fuel, I get 30.4mpg but with Esso... 38mpg.
Good fuel has extra additives which supermarket fuel cuts to make it cheaper.
 
miniswift said:
Hi,
I think if you use better fuel, your mpg will increase.
I have outlander PHEV and drive with supermarket fuel, I get 30.4mpg but with Esso... 38mpg.
Good fuel has extra additives which supermarket fuel cuts to make it cheaper.
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Yes I use the Millers diesel additive to replace those additives at far less cost than the difference between tier-1 branded and supermarket fuel. Best of both worlds.
 
donp38 said:
don't forget....domestic electric has gone up 30-50%....think of the charging for those?
And the range will only get less with battery age...
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The mining for cobalt etc and also humanitarian devastation to produce batteries for electric cars is a complete no-no for me. You can argue fossil fuels are damaging too, but until somebody creates a clean hydrogen fuel and manages to keep the energy elites happy at the same time, I think sticking with the A2 is better for the environment. If they can eventually force electric on all production vehicles who knows? Until then, I’m quite happy with the little 3 pot.
 

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froggy said:
The mining for cobalt etc and also humanitarian devastation to produce batteries for electric cars is a complete no-no for me. You can argue fossil fuels are damaging too, but until somebody creates a clean hydrogen fuel and manages to keep the energy elites happy at the same time, I think sticking with the A2 is better for the environment. If they can eventually force electric on all production vehicles who knows? Until then, I’m quite happy with the little 3 pot.
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Exactly my sentiment, it sjust the emission that get headlines, there more to it..
 

Fuel consumption on small DIS

Today i tried to add fuel consumption line in my small DIS and it worked! 2001 AMF. Thanks to @bono05 for this information. You need to change code in [17] - Instrument Cluster. Need to change last digit to 5. But question is what this change does to a2 besides adding fuel line in DIS? In...
www.a2oc.net

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donp38 said:
I have ordered some
miller additive.....will report back...
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One for the cetane booster thread perhaps, but if the car has not had a diesel purge or any other additives (or you have used standard diesel instead of exclusively using the posh pumps at the filling station), then run the first bottle at double dose, you should get about 5 tanks out of the bottle if used in this way. This gives the Millers additive the ability and time to work at the stubborn deposits - you may not see / feel / hear much difference on the first tankful.

I'd be interested to hear your report on using it - I'm a believer and use it whenever I fill up anywhere other than BP or Shell. Any new diesel car to me I give the above treatment to.
 
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Let's keep this thread on topic for all concerned please - there's obviously a link to increasing energy bills and increasing fuel bills, but the environmental factors recently mentioned are best kept to a separate thread. Further thread swerves/ U turns may well be deleted and the relevant actions taken.

Back on topic, Tank get's a solid 48-50 mpg all the time.
 
dan_b said:
Hi Steve
When I first got my TDi I was also getting low-50s. A combination of a few mods, a few bits of maintenance, plus an evolving driving style, has seen my average MPG go up fairly significantly.

Low-50s is actually pretty reasonable if you think about it, there aren't that many cars that can churn that sort of average MPG out without too much effort. However, if you want to chase higher MPGs, you could consider the following:

1. change the thermostat and temp sender - even if they're not showing as particularly off, there could be an underlying pathology here - the A2 is rather renowned for the stats and temp senders going technical, and they're cruicial for maintaning optimum MPG.

2. consider fitting the 1.2TDi aero mods - wheel arch lip spoilers, sub-frame spoiler and exhaust tunnel cover. It improves the aero a little and might give you a bit of an MPG boost.

3. increase your tyre pressures - I used to run my 15s at 42PSI. MikeMars runs his 15s at 46PSI. Higher tyre pressures reduces rolling resistance and improves fuel economy. Try it - it's free!

4. Switch off air-con until engine is up to 90.

5. Switch off the engine at traffic lights/jams (if you think you'll be stopped for more than 20secs).

6. Splurge big bucks on a transmission mod to lengthen gearing - either a longer 5th gear (which is what I've done) or adding in an extra 6th gear (which is what MikeMars and Timmus have both done).

7. Be really obsessive about eeking out more miles from modifying your driving style - eg. experiment with pulse&glide, working out where you can use overrun fuel-cut off mode, lighter acceleration, change up earlier etc...
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I'm sure running with over pressured tyres will reduce fuel consumption. But when you can't stop as quickly as you thought, you'll realise that increasing the pressure decreases the contact patch! The tyre will also wear quicker due to reduced contact patch, and if you're really unlucky, the tyre could overheat.
Still, you've saved a few pence on fuel.
Mac
 
PlasticMac said:
I'm sure running with over pressured tyres will reduce fuel consumption. But when you can't stop as quickly as you thought, you'll realise that increasing the pressure decreases the contact patch! The tyre will also wear quicker due to reduced contact patch, and if you're really unlucky, the tyre could overheat.
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During regular "every-day-use" one will generate more heat to the tire by running with low pressure, compared to running tires with high pressure. Most of the heat is created by the deformation of the tire when in contact with the tarmac.
 
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