125TDI Improved Fuel Economy After Long Drive.

[Amalgam]

Hi All,

Firstly, Merry Christmas.

I have just returned from a Christmas driving holiday to stretch the legs of wagon. The car had travelled 5500km prior to the road trip and was returning a fuel economy in the mid to high 6L/100km from mainly urban driving with the occasional freeway cruise to Mandurah which is 100km from Perth for a seafood lunch and to passive regen the DPF, just to be safe. No dashboard error lights ever illuminated.

On our 350km drive to Margaret River to sample the wines, , the car was showing 7.8L/100km. Not bad I thought considering there was 3 onboard, a fully loaded cargo area and the airconditioner working hard to keep us cool. There was a slight hesitancy on acceleration but nothing that I didn't put done to a near full load.

On the return trip, I brought back friend and his luggage, which added an additional 110kg to the weight and the temperature was even hotter peaking at 39C. To my surprise the fuel economy improved to 5.8L/100km and the car was pulling like the 3.0L Outback that the Passat replaced.

In short, it took 50L of Vortex diesel to travel almost 900km and the engine performance improved after a long run.

Cheers.

George

[wind]

The economy does improve after you have had a high speed run. Blows the accumulated sh-t out of the engine, i.e. gets everything 'cleaned' up by doing a long drive where all the deposits that have built-up from short runs gets the combustion treatment (i.e. burnt).

When on longer runs, I tend to keep the revs in the most efficient range (1,800-2,000+ rpm) with a load on the engine for extended periods of time, which is where optimum combustion (and economy) occurs, with revs below 1,800 rpm you would typically be generating more soot (i.e. which will be caught in the dpf and will decrease the interval for regens to occur) - that is why it is advised that you take the TDI (and all cars in general!) for a 1-2 hour high speed run on a regular basis.


Myself, have done just over 17,000 km in 6 months (mostly long trips with about 20-30% mixed city driving). The economy has been speed dependent - if I am cruising at a constant 90 km/h (or less) then I am getting below 5l/100km . . . on the other hand, if I am cruising at 110 km/hr (or a little above ) then the economy goes to around the 5.5-6.5l/100 km mark. This is all with air-con running as well as not being gentle on the accelerator when overtaking or needing to do a twisty (i.e. fun) section of a road (the car is normally loaded with gear - equal to 2-3 passengers). Admittedly, most of the driving would be with the adaptive cruise on. In smooth flowing city traffic (with the odd red light), I have managed to consistently get between 4-6 l/100km - with heavy traffic this would increase to between 6-8.5 l/100km (rarely going higher unless it is some serious stop-start gridlock involved!).


Re tank range - I am getting about 800-900 km from a tank (from filled to the brim until I get the empty light) in mixed city driving and easily 1,000-1,100+ km when cruising interstate. My economy was pretty good from the start (did not baby the engine, other than basic precautions as per manual). In the first couple of weeks of getting the car: my first run was about 7.0 l/100 km (900 km run, this was a couple of days after I got the car, it had just 200 km on the clock - full car), the second run (return leg of first run) got 6.5 l/100km, third run was about 6.0 l/100 km (another 1,000 km, with load) and the return leg of that was giving me under 6l/100km. Since then the economy has been consistent - would improve if I cruised at a lower speed, but I like to travel at the (license preserving) speed limit . . .

[dopey]

I did 2200km worth of driving in my 125TDI Wagon this week. Sydney to Melbourne and return, plus driving around in Melbourne whilst I was there.

Car had 23000km on it at the start of the trip FYI.

The cargo area was loaded floor to roof with luggage, 4 Adults (incl myself driving) + Baby on board, Air con pumping at all times and I managed to get 1100km out of around 62L (I didn't run it dry before refilling). Both 1100km stints had a bit of sitting in traffic/city driving mixed in too.

Overall, very impressed with it on the highway. I usually only get around 700-750km from the same sort of fill around town as I spend a lot of time in gridlock and refuse to use the stop-start as it drives me mad.

It's on the highway/motorway out of the traffic that these cars really make sense. I'm looking forward to more road trips now.

[Transporter]

You always get better economy on long runs on highway, since the engine use a lot more fuel on accelerating from 0km/h. On highway you don't stop and go as many times as in the city driving.

[wind]

I usually only get around 700-750km from the same sort of fill around town as I spend a lot of time in gridlock and refuse to use the stop-start as it drives me mad.

Yeah, the stop-start can be annoying BUT it does help the economy (I get 800+ km around town) . . . works best when it is cooler. On hot days, the engine re-starts more often before you are ready to move (for air-con compressor). The most annoying thing about the stop-start is the lag between when you are ready to go and when the car is (i.e. time to start, get the clutch ready and then engage) - would be OK, but there is a small amount of variability in this time so that every now and again I am on the gas before the clutch engages and have a small jerk (brings back memories of learning to drive in a manual!).


Re road trips - fully agree. It is a great car for when you need to do long distances. I have the sports seats and on my longer trips: say Sydney to Adelaide (approx. 14 hours driving + breaks) I arrive in very good condition - fresh/relaxed compared to other cars I have driven. In some renters I have had - was a constant 'struggle' driving them and after 3-4 hours was b-ggered and had to have a long break just to recover before I could continue!

[cru22z]

just came back from Syd - Mel - Syd trip and used only 1.5 tank of diesel. cruising on 110-120kph, 2 qdult 2 children boot full with aircon and some gadgetry running all the time. one the way home only used 1/8 tank from mel to syd.

[brad]

5500km = engine still running in. Will continue to improve right through to the 15,000km service

[Marakai]

just came back from Syd - Mel - Syd trip and used only 1.5 tank of diesel. cruising on 110-120kph, 2 qdult 2 children boot full with aircon and some gadgetry running all the time. one the way home only used 1/8 tank from mel to syd.

Wait. Roundtrip you used 1.5 tanks, but 0.125 in one direction? Meaning the rest (1.375 tanks) you used Syd-Mel? That's a heck of an imbalance! Didn't think Sydney to Melbourne was all uphill all the way!

[Guest001]

Measuring consumption by the tankful is the most imprecise way of doing it anyway.

Unless readers know what size tank you have it really means nothing.

For instance I got from Brisbane to Coffs Harbour and back on less than a tankful in my new Passat.

However I also did the same in my 100 ser Landcruiser.

Sounds OK and similar doesnt it.

Difference is that the Passat has a 77ltr tank and the Cruiser has a 145ltr tank

Actual consumption was 5.53L per 100km for the Passat and 10.6L per 100km for the Cruiser which puts a totally different slant on things doesnt it.

Unless you fill it till you can see it before and after and then work it out you could be way way out.

[Amalgam]

Hi All,

I was so impressed with my last run to Margaret River and because the weather in Perth was predicted to be over 39C for 4 days that I decided to spend New Years at Albany which is 440km south one way. With 2 side trips, we clocked just shy of 1200km at 5.5L/100km and once again not sparing the horses.

Really impressed by the economy, performance, ride and NVH.

Cheers.

[rory]

Found on my 1.6 litre TDI Jetta with DSG that lives in the country and almost invariably is sitting on 100 or 110 really drops consumption on a coastal cruise (no hills) and a tailwind ; down to 4.6 l/100k and once even 4.4 for a tank. Into wind it returns 5.0 on coast runs. I generally get 5 to 5.2 litres average per tank . 110 000 ks on the clock

[Diesel_vert]

Hi All,

Firstly, Merry Christmas.

I have just returned from a Christmas driving holiday to stretch the legs of wagon. The car had travelled 5500km prior to the road trip and was returning a fuel economy in the mid to high 6L/100km from mainly urban driving with the occasional freeway cruise to Mandurah which is 100km from Perth for a seafood lunch and to passive regen the DPF, just to be safe. No dashboard error lights ever illuminated.

On our 350km drive to Margaret River to sample the wines, , the car was showing 7.8L/100km. Not bad I thought considering there was 3 onboard, a fully loaded cargo area and the airconditioner working hard to keep us cool. There was a slight hesitancy on acceleration but nothing that I didn't put done to a near full load.

On the return trip, I brought back friend and his luggage, which added an additional 110kg to the weight and the temperature was even hotter peaking at 39C. To my surprise the fuel economy improved to 5.8L/100km and the car was pulling like the 3.0L Outback that the Passat replaced.

In short, it took 50L of Vortex diesel to travel almost 900km and the engine performance improved after a long run.

Cheers.

George

I'd say that's very normal.
The brochure states 6.7 l/100km for urban and 5.7 l/100km for combined, so your figures are pretty much bang on.

You will always use a lot more fuel in urban areas because of all the acceleration bursts, compared to steady state highway driving.

[sn809]

Most new cars dont match brochure stats as far as I know but that may just be me.

A suggestion either of you tried running with Morey's Diesel Engine Smoke Killer?? I did after reading up and getting advice from Transporter on VWW, does wonders for my old Passat. Read up and try.

http://www.vwwatercooled.com/forums/f77/diesel-fuel-additives-14355-2.html

[Diesel_vert]

As his car is still almost brand new and nothing much wrong with it, I wouldn't think he would need to use fuel additives at this stage.

[Transporter]

Hmm, I disagree. The deposits are formating and starting to clog the emission devices like DPF from the day one the engine is made and started up, so why wouldn't you help it to stay in peak condition for longer? Also, your DPF could last longer too.

But, ofcourse if you're rich enough and buy a new car every 3 years then why would you bother with some additive and better fuel economy.

Additives by LIQUI MOLY