Quoted MPG - how accurate is it?

Imperial

Full Member
Jan 10, 2006
121
7
No I'm not impressed either.

I will be starting its deep clean this weekend after a few hectic weeks. The plan this week is all four wheels off, clean, decontaminate & wax front and back, wheel arches cleaned out & decon including arch liners off & refitted. Repaint brakes, including the exposed rusty bits of the discs and dress all arch plastics & wishbones etc.

Interior I have done already including a steam clean. Under bonnet and door shuts already done. Next weeks long weekend will be full machine polish. After all that I'm hoping I have more love for it and can see past the worse than expected mpg!
 

KXL

KXL
Dec 15, 2016
1,581
197
London, UK
Well, another record, 64.6 mpg on a 1.0 TSI DSG. So either the trip computer has gotten more optimistic, the temp is 'just right' for max economy, or the car has hit 8k miles, and has losened up. Using Esso 95, no fancy 'premium' 97/99 RON stuff.
 

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camelspyyder

2 SEAT-er
Jun 26, 2014
1,305
175
Well, another record, 64.6 mpg on a 1.0 TSI DSG. So either the trip computer has gotten more optimistic, the temp is 'just right' for max economy, or the car has hit 8k miles, and has losened up. Using Esso 95, no fancy 'premium' 97/99 RON stuff.

...and at a mighty average speed of 25mph. Not a massive sample 12 miles is it? Is your commute downhill lol?
 

KXL

KXL
Dec 15, 2016
1,581
197
London, UK
...and at a mighty average speed of 25mph. Not a massive sample 12 miles is it? Is your commute downhill lol?

It wasn't downhill per say, just lack of traffic and people hitting the brakes for no apparent reason. Half the journey was 40-50 mph roads, and rest were 20-30mph. I think there was only 5 traffic lights that turned red in that time. But I hear ya, that 12 miles is a bit low and slow for a mpg run, maybe a bit further and faster is more realistic. When keeping a steady speed, around or close to 60mpg average is possible. When constantly accelerating and decelerating, well, it's not going to be.
 

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KXL

KXL
Dec 15, 2016
1,581
197
London, UK
Well I finally managed to do this exercise of comparing the actual mpg vs indicated mpg (on the car display). Filled the car till the 'click' previously, and drove 408 miles, and finally refueled again. Actually the thing 'clicked' around just under £51 mark, at £50.85. Tried unsucessfully to round it up till £51.00 and again to £51.50. Anyway, taking it at £50.85 @ 1.279 gives me 39.75 liters.
This would mean (if I've done the calculations right) that the actual mpg would be 46.67mpg whereas the car display showed 47 mpg. The difference is less than 1%. Is it just me with an accurate gauge? Or did I do something wrong?
 

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carlos47

Active Member
May 3, 2018
3
0
I thought the on-board mpg display was fairly accurate when I checked last year, within 1-2mpg. I'm going to re-check after some of the comments here, it doesn't feel way out like the on-board estimates of older cars.
Now over 1 year old my 1.2 TSI is high 40s with mixed use. If doing economical A-road driving I've seen it push up to 60, at least mid-50s for a 80mile trip. Inner city driving, lots of stop start and traffic, usually is around 30mpg, dropping into the 20s the shorter the trip!
 

KXL

KXL
Dec 15, 2016
1,581
197
London, UK
I thought the on-board mpg display was fairly accurate when I checked last year, within 1-2mpg.

Perhaps even the petrol station pump may be not 100% accurate either...I once went into an Esso garage, that had the 'old school' pump where the numbers would physically change by flipping over ot the next number (with a sound). Not sure how accurate they were.

I found my car most economical doing 30-50mph (constant and no traffic). 60-70mph, would see close to and just under 50 mpg (on the readout).
 

camelspyyder

2 SEAT-er
Jun 26, 2014
1,305
175
Good numbers, seemingly accurate, the only variable being the pump. Do they all click at the same back pressure? I know it's OCD but I used to brim to brim measure using the same pump.

Using the real time display, I once saw 7mpg on the 1.2, and I wasn't even flooring it.
 

Imperial

Full Member
Jan 10, 2006
121
7
I've just finished my tank of super and refilled. Got indicated 59.5mpg and actual of 54.8mpg. So a little better but not worth the extra cost. And I reckon some of it is me getting better at managing the loud pedal. So gone back to normal unleaded to see.
 

camelspyyder

2 SEAT-er
Jun 26, 2014
1,305
175
That's really good. If you were driving a 1.2 or 1.0 TSI you'd be really surprised to beat that. I never have in 4 years.

Even the 1.6TDI isn't renowned for an overall figure much better - and it sounds like a concrete mixer, and is heavy enough to hurt the handling ride and tyre wear too. ( just in case you're considering going back to the dark side)
 

camelspyyder

2 SEAT-er
Jun 26, 2014
1,305
175
Well I finally managed to do this exercise of comparing the actual mpg vs indicated mpg (on the car display). Filled the car till the 'click' previously, and drove 408 miles, and finally refueled again. Actually the thing 'clicked' around just under £51 mark, at £50.85. Tried unsucessfully to round it up till £51.00 and again to £51.50. Anyway, taking it at £50.85 @ 1.279 gives me 39.75 liters.
This would mean (if I've done the calculations right) that the actual mpg would be 46.67mpg whereas the car display showed 47 mpg. The difference is less than 1%. Is it just me with an accurate gauge? Or did I do something wrong?

So your whole tank figure is 47:thumbup:. From my 1.0 experience that sounds much more realistic than some of your other posts.
 

Imperial

Full Member
Jan 10, 2006
121
7
That's really good. If you were driving a 1.2 or 1.0 TSI you'd be really surprised to beat that. I never have in 4 years.

Even the 1.6TDI isn't renowned for an overall figure much better - and it sounds like a concrete mixer, and is heavy enough to hurt the handling ride and tyre wear too. ( just in case you're considering going back to the dark side)
Nah don't think I am. It is a much nicer place to be than the arosa. I've got it nice and clean and enjoy driving it. Only trouble is I have to be careful were I park again. The best thing about the arosa was not worrying where I left it!
 

Superman001

Active Member
Jan 14, 2017
110
15
Paisley
Just manually calculated my first full tank of fuel since getting my 2016 Cupra last week at 37.77mpg which is very close to the trip computer. This was a mix of A roads, B roads and Motorway and 3 62 mile round trips to work.

James
 

KXL

KXL
Dec 15, 2016
1,581
197
London, UK
So your whole tank figure is 47:thumbup:. From my 1.0 experience that sounds much more realistic than some of your other posts.

That's right, 47 mpg for a tank is not bad for city driving in London with an average speed of 24km/h. As @ imperial mentioned, mid-to high 50s mpg wise is possible, but patience is oh so tiring (at least for me) to achieve close to 60. The high mpgs are what the engine could theorethically achieve in the real world if conditions are right (eg..no traffic). You are absolutely right, my previous figures are not as realistic due to the fact that driving around with no traffic around you all the time is. Rush hour central London traffic crawl for a couple of miles...less than 30mpg is possible, unless one has a hybrid set to EV mode only, which was exactly what I was thinking when I was stuck in traffic with start stop...well more stop than start.

Anyhow, my next car may be a 1.8TSI / 2.0TSI engine....I will be happy to even nudge 40+mpg on any run haha...
 
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KXL

KXL
Dec 15, 2016
1,581
197
London, UK
I've just finished my tank of super and refilled. Got indicated 59.5mpg and actual of 54.8mpg. So a little better but not worth the extra cost. And I reckon some of it is me getting better at managing the loud pedal. So gone back to normal unleaded to see.

Which of the Super Unleaded did you go for? Shell 99 / Esso 97 / Momentum 99?
 

KXL

KXL
Dec 15, 2016
1,581
197
London, UK
It was the esso, so granted not the best of the 3.

My personal experience is that Esso 97 gave the smoothest engine (less judder on low rpms), Shell Vpower 99 gave the most mpg, and Momentum 99 gave nothing at all except a higher fuel bill over Esso/Shell/BP 95.
I can't comment on power gains as I did not feel any difference..
 

camelspyyder

2 SEAT-er
Jun 26, 2014
1,305
175
Shell Vpower gave me the 6% economy increase over Shell95.

Cant say it was smoother or quicker since the chain 1.2 TSI is the smoothest 4 cylinder I ever had anyway.
 

Imperial

Full Member
Jan 10, 2006
121
7
Indicated 58.3mpg, actual 53.8 back on standard unleaded. My aim is to get 600miles out of a tank.
 

camelspyyder

2 SEAT-er
Jun 26, 2014
1,305
175
54.8 or 53.8 is pretty good but you wanted 60+ ?

Is that really how the FR is designed to be driven? I reckon I'd probably not beat 40 in that car.
My 1.2 Toledo got down to 39 or 40 when I was in a mood to have a fun 40 minute drive to work.
 
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