Technical Accuracy of MPG readout

[disgusted]

I like people who do brim-to-brim checks!

That was my reason for starting this thread in the first place. I reckon that my read-out is a constant 8% pessimistic.

 

[FatBoab]

Recently bought a cheap 2001 110 1.9 JTD ELX, 154,000 miles. I serviced oil, filters plus timing belt/tensioner/idler/water pump, new tyres.
Tyres at 2.3 bar as per handbook. Glow light stays on for a whilst after starting, sometimes flat spot in 2nd gear but car drives well.
Trip to visit family carrying 3 adults/3 sets of golf clubs/3 cases.
Brimmed it before leaving and did 550 mostly motorway miles at gentle legal mph in 8.5 hours.
Fuel light came on as I arrived so I brimmed it again with 60 litres, manual calculation is 41.6 mpg however car computer showed 46.2mpg which is about 10% too optimistic.
What can I do to improve mpg on return trip?
Cheers

 

[pete123]

Don't drive up hills lol not bad the readings are out there is a way to work this out if u read some threads if u want to increase the numbers don't wellie the car up to speed I've had 55mpg out of a 110 sx

 

[pete123]

Just been reading up on a app on my phone some person reckons there 110 jtd has a tank range of 711 miles is this possible because it sounds to good to be true

 

[rc3675]

Based on 13 gals (I think it's a bit more) for the fuel tank size, plus the 55mpg that you've previously quoted, that gives 715 miles range.

 

[pete123]

No wonder everyone wants the diesels I no they got 70 litre tanks on them so is that 13 gallons fitting in the tank

 

[rc3675]

They've a 63 litre tank.
As there's 4.54 litres in a gallon, that's 13.9 gallons

This means
at 50mpg, the range is 695 miles
at 45mpg, the range is 625 miles
at 40mpg, the range is 455 miles

..and at your quoted 55mpg it's a potential of 763 miles. But please don't try to prove it as I'd hate for you to run out of fuel! :bang:
Figures are all theoretical. Reality is based so many more variables - after all how many hils can you not go up in 700 miles?

 

[rc3675]

Recently bought a cheap 2001 110 1.9 JTD ELX, 154,000 miles. I serviced oil, filters plus timing belt/tensioner/idler/water pump, new tyres.
Tyres at 2.3 bar as per handbook. Glow light stays on for a whilst after starting, sometimes flat spot in 2nd gear but car drives well.

Sounds a nice car, and looks like you intend to keep it that way

Trip to visit family carrying 3 adults/3 sets of golf clubs/3 cases.
Brimmed it before leaving and did 550 mostly motorway miles at gentle legal mph in 8.5 hours.
Fuel light came on as I arrived so I brimmed it again with 60 litres, manual calculation is 41.6 mpg however car computer showed 46.2mpg which is about 10% too optimistic.
What can I do to improve mpg on return trip?
Cheers

I average approx 45mpg (and computer always shos 10mpg less!) which doesn't seem to change much if it's a long motorway journey or a commute across a variety of A / town / city roads.
It does however do less if: 1) it's all very short town journeys, or 2) the faster I go on motorways 3) it's winter
I've had 42mpg on holiday trips before, so don't worry about that.
One other thing I've noticed is that it's not always easy to brim the car to the same level (depends on where the pump clicks off) and just a couple of litres can make a massive difference to your calculations. Try filling up again when you get home (at your usual pump) and take the calculation across both tank fulls.
Let us know how you do.

Hope you continue to love the car for a long time to come

 

[FiatFleetFamily]

They've a 63 litre tank.
As there's 4.54 litres in a gallon, that's 13.9 gallons

This means
at 50mpg, the range is 695 miles
at 45mpg, the range is 625 miles
at 40mpg, the range is 455 miles

..and at your quoted 55mpg it's a potential of 763 miles. But please don't try to prove it as I'd hate for you to run out of fuel! :bang:
Figures are all theoretical. Reality is based so many more variables - after all how many hils can you not go up in 700 miles?

And if your engine is nicely run in, more mileage on engine and well serviced equals a good return on diesel fuel used. Mine is still being run in and not anywhere near 30k yet!

 

[BikeDoc]

...What can I do to improve mpg on return trip?
Cheers

Find a Coach, preferably a double-decker, and slipstream it.
I can get over 60mpg (indicated) on a motorway trip doing that

I prefer to have the 'Range' function showing, it reacts quicker than the mpg one, and gives a much clearer indication of how much fuel you're burning.
E.g. Driving around locally it'll show a range of, say 350miles, but if I then get on the motorway and settle down to a steady 60-odd mph, within minutes it'll be up in the high 400s.

 

[sweetex john]

my multipla eleganza loves the motorways, even in limp mode it still comfortably does 70 mph... it does 80 mph really, but who would admit to breaking the law

 

[Pandabloke]

I owned Myrtle, a 2008 Eleganza 120 Multijet, from 7500 up to 125,500 miles. In that time the brim to brim measurements showed a consisistent 40-45 mpg, with the occaisional foray into the high thirties and the high forties. Basically, she used to average about 42mpg in daily driving. This was with mixed, town, A+B road and some motorway work, a real variety.

I once achieved 56mpg for a tankful whilst crawling to and from at 50mph from Kent to Devon (5 hours each way, never again...). I also did the same journey, covering the 512 miles at the full monty (and much more) giving a total travelling time of not much over seven and a half hours (don't tell the plod....) and I got under forty to the gallon.

But essentially, if anyone asks me what to expect as average mpg from a 120 Mutijet, I'd say 42mpg, cos I'd confidently expect to get that regularly from day to day driving. (that's brim to brim, not using the MPG feature....)

Panda.

 

[DiamondDave]

On this subject, I've done a little bit of a test with a full tank. In the images the readout says 16.7 km/l and when converted to miles, 39.2 MPG.
I used an online converter (below) and converted 16.7 km/l to MPG-US and MPG-UK. It truly is the US Gallon!
The car actually did 940km for 60l, which is 15.7 k/l or 44.3MPG-UK which isn't as good as the km readout says.

https://www.unitjuggler.com/convert-fuelconsumption-from-kmperl-to-mpgimperial.html?val=16.7

 

[MrFlibble]

I wish I'd read this thread before, especially the last post. Had I known I was getting 46mpg out of it I wouldn't be buying a new car and putting the multi up for sale.

 

[spudit2003]

Just bought a Multipla JTD M 120, glad ive seen this as i was a bit concerned about my 37mpg readout. I got it so i had a more economical car than the Avantime which fitted everything in, and the Avi will do 37 at a push. So can hope for high forties on the cross country runs to see in-laws.
I expect the programmer just googled litres to gallons and had no idea there were different sized gallons!

 

[Multapunkata]

My computer is about 3mpg pessimistic, 42-45mpg is normal for Norfolk driving.
However, if you want to see 18mpg and an overheating engine, tow a heavy or high-drag trailer at 60mph. Towing needs to be done grievously slowly to avert fuel disaster.