Yes, simple math should confirm your MPG.
......

 

I can't be sure because I don't own an ultragauge, but I use a bluetooth OBDII adapter and the program Torque. Torque's mileage and gas consumption numbers are incredibly inaccurate.

To calculate your mileage - fill the tank up, reset your odometer, drive for a while, fill it up again. Then divide the number of miles you drove by the gallons you refilled it with.

Odds are you are getting somewhere between 11 and 15 mpg.

 

But if you have larger tires it will be off

 

100 liters! Remember its a European vehicle.

 

RAVE says its 95 liters(UK\EURO\ROW) or 25.5 gallons (NAS), but google tells me 95 liters = 25.09 gallons?

 

UK and US gallons are different.

 

Ultra-Gauge is setup correctly for a 25 gallon fuel capacity etc. I definitely dont floor the gas either. Im running thin 235/85R16 mud terrains though. Also have a winch bumper, roof rack, 4 jerry cans, 3 wolf pack storage bins and a bunch of **** inside the truck.

Im getting some fault codes which Im currently working out in another thread: https://landroverforums.com/forum/di...s-codes-81404/

Im going to replace the sai pump and a hose followed by a new y-pipe and see if that resolves the faults and restores my mpg. Gonna be afew weeks though.

Still pending on the math, filled the tank full and waiting until the fuel light comes on before I figure out the current mpg.

 

The fuel consumption that is reported by your Ultragauge is off, as is the reported mileage on your odometer, due to the addition of oversize tires.

I get this as well. 52mph indicated on my speedometer equates to 60 mph by GPS. For ever mile traveled, my Odometer registers about 8/10's of a mile. This plays havoc with mpg calculations unless you use a GPS to calculate actual miles traveled. The way i figure out my real mileage is by tracking actual miles driven via GPS and divide it by the amount of gas i've had to put back into the tank to fill it. With my heavily laden truck i'm getting just over 11mpg in mixed driving. My Ultragauge reports 10.3.

According to my math, you should be ~8.6% under on your speedometer and odometer with your current tire size, but that still seems low for fuel consumption.

 

I just upgraded to larger tires and noticed that the same trip I've been taking across the state for years is now shorter!! Previously 335 miles, now 297!!!

I knew my speedometer and odometer would change but was still surprised to see it. I also thought maybe the UG would change, as it always has read 5mph lower than the speedometer. It still does, that has not changed.

I noticed that I was passing everyone on the road while the UG was saying I was going the speed limit ;-) I don't think the State Trooper would buy my excuse!!

I will have to use a GPS or do the old time per mile test to see what my error rate and actual speed and miles per gallon are.

I did notice lower MPG as the low fuel light came on before it normally does on this trip. but maybe that was the headwind and my excess speed!!!

 

Alright so my figure is about 6.85 mpg. Last week I waited until the fuel light came on then filled up until full (21 gallons) and reset tge odometer. Today the fuel light came on and I had 144 miles clocked. However this past week has seen some very cold night's (30 degrees) so figure in 2 hours of idling into the equation. Not sure how to figure out how much fuel us consumed while idling wirh the heater blasting, maybe add 5-10 extra mikes to the 144 and we get somewhere around 150-155 miles on a tank of gas. Most of my driving is city and most of the time I have my beloved heater on full power. Also my tires are due for replacement and the air leak in the SAI pump, and finally my cats are on the way out.

The Disco is getting bew cats, tires and SAI pump in afew weeks so that should improve my MPG noticeably.

Thanks for the feedback and suggestions.