For the past couple of months we've been using the 1.6 tdi for motorway journeys only. And every time the Maxidot show the average MPG in the  70s which is hybrid car performance, however, when you actually do the maths on a full tank (until it hits reserve) gives us 450miles. Today we did a 200mi round trip 90% motorway at 70mph and it averaged 75mpg apparently. I know cold weather and all of that but the actual consumption is basically the same.

 

It didn't used to be like that, why is it lying this much??

It's possible, particularly if you were on a constant speed, where the engine wasn't really under load, but always apply a pinch of salt. Level senders aren't the most consistant of things, so when it says it's just hit the reserve, there could be any amount of fuel still in there. If you want to know what it's really doing, tank it, do some miles, tank it again and use the amount of fuel you've put in to calculate your MPG. 

Edited 30 December, 20187 yr by StevesTruck

What he said, and long steady speed cruises on a light throttle with a hot engine are always when you get good economy anyway.

I was initially pleased that my new (to me) MK2 Octavia was (allegedly) more economical than its MK1 predecessor despite being a few hundred kgs heavier. i also seemed to be getting much better MPG than those with the same engine/vehicle who posted their results from the Fuelly app.

 

Then I got suspicious, the range was better but the tank is bigger, so I checked a brim to brim fill up and the actual MPG was much lower than the average shown on the dash display.

 

I wondered if I had not completely filled it initially, an airlock perhaps so have done the same on my last 3 tankfulls and it has been between 12% and 15% overoptimistic, averaging at 13%, I reset the odometer and trip computer each time and have carefully brimmed the tank every time.

 

Indicated MPG = 58.5, actual = 51.7 (+12%)

 

Indicated MPG = 55.7, actual = 47.82 (+14%)

 

I am not sure that I ever did the same checks on the MK1 but its range divided by the fill up volume always seemed pretty spot on with my mental arithmatic, this vehicle I knew straight away was telling me porkies.

 

Its not just the emissions that VAG lie about

 

I saw somewhere in VCDS a way to program a correction factor, does anyone know where it is found?

 

My ego wants it to continue tellimg me lies and certainly when I sell it it would be better but that hopefully is years away, I want to have a try at it telling me the truth as i think the remaining miles (range) display might be more accurate and linear once corrected.

Try owning a slightly modified one 

 

I agree, prior to the zorst upgrade I could sometimes nudge 80mpg on the trip computer (in super grandad-stylee mode) on the 50 mile round trip to my mums (M1 from Leeds, M62, then cross-country from Normanton/Castleford junction to Hemsworth). I'm lucky if I hit 65mpg now....... not that I'm really bothered though, the extra oomph more than makes up for it :)

5 hours ago, EggMeister said:

I agree, prior to the zorst upgrade I could sometimes nudge 80mpg on the trip computer (in super grandad-stylee mode) on the 50 mile round trip to my mums (M1 from Leeds, M62, then cross-country from Normanton/Castleford junction to Hemsworth). I'm lucky if I hit 65mpg now....... not that I'm really bothered though, the extra oomph more than makes up for it

too many tunnels

i think there's no point setting the Maxidot on the MPG or Range since it's not even close to accurate.

On 30/12/2018 at 22:58, J.R. said:

I saw somewhere in VCDS a way to program a correction factor, does anyone know where it is found?

 

Yes it can be calibrated slightly with VCDS:

 

 

On 31/12/2018 at 20:26, AMD87 said:

too many tunnels

 

Not many tunnels around here :(

First off, ignore the on-board computer. You're chasing nirvana!

 

Think the most I've had from my 1.6TDI (105PS) was 530 miles... and that was with 10 miles left in tank. That was during the summer, no hard acceleration and steady 50-60mph. You can turn off the air conditioning too if you're a die-hard.

 

Regular oil and air filter changes are a must. Forte diesel conditioner straight into the fuel filter, then drive hard in second and third gears. Renew the filter afterwards and top up with fresh diesel, even VPower if you're feeling flush! Forte is good for lowering emmisions, and no doubt helps clean the injectors. Check the tyre pressures. Basic I know, but good starting point.

 

At the end of day the 1.6 engine is old school technology now. It was never particularly efficient. Relative of mine has Volvo V50 which has 1.6 engine. Now that thing is frugal compared to the Skoda.

For my car (105PS)  when new the displayed average mpg was surprisingly accurate compared to calculations of the mileage between refuelling but now it reads low by ~10% making the disappointing mpg of the 1.6CR TDI seem even worse.

 

On a long freeflowing summer daytime motorway run e.g. M5 Gloucestershire to Exeter and keeping to 70mph I just get 60mpg. On long run but dual carriageway with roundabouts every few miles then less and likewise on single carriageway roads where limited opportunity for 60mph. In winter the mpg drops again partly of course due to the volume of the winter diesel additive. I only run the air-con when required including once every couple of weeks to circulate the system.

 

I don't doubt the basic 1.6CR block is more efficient than the old 1.9PD but the gain is lost due to the EGR, DPF etc hung onto it.

 

Edited 5 January, 20197 yr by delta925

I find it fascinating that no one seems to believe the accuracy of the cars computer mpg readings, and use another inaccurate method of measuring the fuel used (brimming the tank, although it might be slightly more accurate), but then use the same inaccurate 

cars odometer reading to obtain the distance measured (no one seems to question this). Even if the odometer was close to accurate when brand new, as the tyres wear the diameter of the tyres decreases, therefore the distance travelled gets less per revolution.
Whenever i pass a road side digital speed sign at an indicated 30 mph on my speedometer (although you can't guarantee that sign has been accurately calibrated that day either) the sign indicates I'm doing 28 mph. Which means when my odometer says I've travelled 30 miles I've actually only travelled 28 miles.
So unless you're in a lab under controlled conditions, using an accurate method of weighing the fuel used and an accurate method of measuring the distance travelled, you'll never get an absolutely accurate mpg figure.
Better to just enjoy the car and keep an eye on how much disappears from your wallet in fuel bills per month, if that gets too much, you need to get a more efficient car to enjoy.
If it goes down too much, you need to drive faster and have more fun, or risk falling asleep at the wheel 

Odo error is probably less than speedo error. Some kind soul pointed out to me recently that just because they use the same raw data doesn't mean they use it the same way. Speedo is deliberately tweaked cos it's illegal for it to underread. Odo probably isnt.

I had a similar result with 1.2 TSI, in reporting high mpg figures but investigation found that the fuel sensor was faulty. Replacing the fuel sensor cured the high figures, now get maxidot at 45 mpg instead of in my case 65, actual calc is in the region of 40.

Davefra,

 

Your comments are valid.

 

For my car the speedo reads ~5% high at 50 - 70mph, which is reasonable since the law states is must not read low and not more than 10% high.

 

The odometer is more accurate based on distances given by Google Maps. Tyres will wear but a change of 12mm diameter ( 8mm new to 2mm worn ) on a nominal diameter of 590mm is small. The nominal diameter of 205/45/16 and 195/55/16 is close too. I guess VAG work on half worn tyres and the average of the two for design & manufacture.

 

Indeed the actual level at each refuelling will vary. I judge the long term average mpg not individual refuellings.

 

The change I see between the mpg being near to calculations when new and ~ 10% low now is relative.

Cruising at 70mph on the motorway is heavenly territory for a diesel!  Mine regularly shows 70+ mpg on the maxidot under those conditions.  I regularly get 600+ miles from a tank and occasionally 700+ miles.  The Roomster is heavier and less aerodynamic than the Fabia but it has a 55 litre tank vs the Fabia 45(?)  litre.

 

I've always found the Skoda trip computers to be pretty accurate.  I'm something of a nerd when it comes to recording fuel use!  My current 1.6TDi Roomster has covered 55,000 miles and used 4,560 litres of diesel = 54.8mpg.  The average mpg from all the maxidot readings (recorded at each fill-up) is 56.6mpg, or 1.8mpg optimistic.

 

The 2 previous Skoda's I owned  were 3mpg optimistic and 1.9mpg optimistic.

 

The only way to get an accurate comparison is to record and combine data over a few fill-ups. but beware!  If you have the non-maxidot trip computer the long term readout (memory 2) resets after 20hrs or 1999km, whereas the maxidot resets after 100hrs or 9999km.   That means with the standard display you can easily hit the 20hr reset limit within a single tankful, and almost certainly before 2 tankfuls have been used.

 

Another thing to be aware of.  If you are using an app or online calculator to determine your fuel consumption be sure it is using Imperial gallons (4.546 litres) and not US gallons (3.785 litres).  For example using my figures above 54.8 miles per imperial gallon is only 45.6 miles per US gallon.   45.6 would look pretty sick against the maxidot 56.6!! 

I do 35k miles a year and on my daily run to work hit 70 mpg going 60mpg - I drive a 1.6 TDI.  Overall I get about 63.5mpg

23 hours ago, Asketi said:

I do 35k miles a year and on my daily run to work hit 70 mpg going 60mpg - I drive a 1.6 TDI.  Overall I get about 63.5mpg

 

how many miles do you get per tank? until it hits the first red line.

675 roughly

 The above post about motorway driving is absolutely spot-on. By 1.6 tdi  just cruises effortlessly and reasonably quietly on the long motorway runs.

 

Almost all of my daily commute is on the M11 which is not hilly.  

 

 In terms of bang for buck my Fabia Is easily the best car I have ever owned. This is especially the case because of the cheap servicing, zero defects and superb fuel economy 

13 hours ago, Asketi said:

675 roughly

wow that is very good 

AC off

tyres at good pressure

gentle driving

oil and filter ever 10k

 

 

plus I do almost all driving at 70mph

 

i recon it takes 15 - 20 mins at 70mph for the old girl to get fully up to temp

2 hours ago, Asketi said:

AC off

tyres at good pressure

gentle driving

oil and filter ever 10k

 

 

plus I do almost all driving at 70mph

 

i recon it takes 15 - 20 mins at 70mph for the old girl to get fully up to temp

 

that's what I normally do. 500 at best.

Last weekend I had a long return trip mostly motorway or dual carriageway with flying junctions rather than roundabouts and with this thread in mind recorded the following:-

 

Distance by Google Maps 137 miles. Car recorded mileage 137 out and 136 return.

 

Car recorded average speed out 61mph and return 58mph, which is about right for distance / time rather than from the speedo which reads ~5% high.

 

Car calculated average mpg out 50mpg and return 52mpg.

 

I filled up the day before and again the day after with 22.07 litres. With local trips 281 miles travelled.

This works out at 58mpg.

 

From this the car calculated mpg was around 13% low.

 

Of course the exact level after each fill up will have been different and 1 litre less used would give 61mpg. However just under 60mpg fits into the bigger picture. Winter diesel will have given a slightly lower mpg too.

 

With diesel still priced 8 - 9 % dearer than petrol a significant proportion of the mpg gain of diesel is cancelled out.

 

The car was serviced last week plus I checked tyre pressures the day before. The aircon was off.

 

 

Edited 5 March, 20197 yr by delta925
typo