3.0 TD Fuel Consumption

[Surf01]

Just my tuppence worth....

My 3.0 3rd Gen auto managed 400 miles to a tank full abroad when i went to the South of Spain and back recently. That's with a bootfull of heavy gear, stuff on the back seat, and the missus riding shotgun. I'm sure i got very close to properly empty as the empty light stayed on and the guage needle stopped moving completely.

On a recent rip to Scotland with just the dogs in the boot and a few bits of gear on the back seat, plus the missus riding shotgun i got to 400 miles and the opportunity arose to fill up again so i took it but there was still fuel showing on the guage and the empty light had only just that second come on.

On both occasions i was keeping a steady 70-75 mph, under 2500 rpm. Around town and countryside driving i'm seeing about 330-340 miles to a tank and the gauge has stopped floating about on empty, empty light permanently on, not going off round some corners.

400 miles on a run is a very useful range indeed having come from a thirsty modified Impreza that just about managed 280-300miles on a steady run and considerably less around town & country.

I only wish the tank was 100ltrs instead of 65. That would really make it a proper intercontinental oil burner with about 600 miles to a tank, and i might only have to fill up once a month or so while at home.

Incidently, does anyone know for sure how much fuel is meant to be left in the tank when the empty light comes on?

If you have the spare mounted on the rear door, I wonder if it is legal to fit another fuel tank underneath as that would change the kerbweight of the vehicle and also have a knock on effect on the maximum gross train weight and others.

[ROMEROTECH]

An extra 35ltrs is about 70lbs (32Kg) in weight. Add to that the weight of the tank, straps, bolts, fuel piping, whatever that will be in total, and i don't think it's going to be a huge amount. Perhaps the weight of a small adult or a large child, depending how many pies they've consumed

I suppose you could always have a custom 100ltr tank made, sounds expensive to do though if a small 25ltr stainless steel race tank is anything to go by.

I've got 3x20ltr green jerry cans. Perhaps i'll just get some brackets/straps made up to clamp up a couple of tanks in the boot. That would work.

[TonyN]

If you have the spare mounted on the rear door, I wonder if it is legal to fit another fuel tank underneath as that would change the kerbweight of the vehicle and also have a knock on effect on the maximum gross train weight and others.

Dosn't really matter, the GTW dosn't change, just the load you can carry is reduced by the weight of the extra full tank of fuel if its full up. No one really pays any attention to the kerb weight.

I've fitted two Long Ranger Tanks for people that go between the spare and the chassis. They are very good, if expensive to fill! Andy Lala had one, he maxed out the amount of fuel the pumps dispence in one go and always had to pay in two goes to fill up from empty.

[ROMEROTECH]

Dosn't really matter, the GTW dosn't change, just the load you can carry is reduced by the weight of the extra full tank of fuel if its full up. No one really pays any attention to the kerb weight.

I've fitted two Long Ranger Tanks for people that go between the spare and the chassis. They are very good, if expensive to fill! Andy Lala had one, he maxed out the amount of fuel the pumps dispence in one go and always had to pay in two goes to fill up from empty.

How many ltrs are these Long Ranger tanks and how much are they?

[Ploddit]

http://www.thelongranger.com.au/4run...efueltank.html

[ROMEROTECH]

Blimey, or Streuth even, an extra 130ltrs sounds very useful. c.1200 miles distance for your average 3.0Ltr Surf means i could almost have got to my destination in the South of Spain on one fill. Just 300 or so miles short. I could do scotland borders and back to Northampton twice on one fill. It takes me anywhere in europe and as far as poland on one fill.

Europe still seems small though compared to Australia. I suppose 1200miles out there is nothing!! That sounds like a modification well worth doing.

When armageddon comes and you have to convert your Surf into a Mad Max machine you're going to need big tanks to get away from all the nutters!!..lol...

[Surf_MoFo]

the speedo reads about 5-7mph out compared to gps, so how accurate will the actual miles you travel be.

[Surf01]

Speedo should not affect mileage reading unless tyres are changed to a bigger or smaller type and then it is fractional.

[Surf_MoFo]

Speedo should not affect mileage reading unless tyres are changed to a bigger or smaller type and then it is fractional.

whatever is telling you the speed your doing im assuming is calculating your distance, if one is out its highly likely the other is out too.

[IanB2]

Speedo should not affect mileage reading unless tyres are changed to a bigger or smaller type and then it is fractional.

whatever is telling you the speed your doing im assuming is calculating your distance, if one is out its highly likely the other is out too.

Agreed, speedo will be tied to odometer, if one is out, so will your mileage calculations.

[Surf_MoFo]

Agreed, speedo will be tied to odometer, if one is out, so will your mileage calculations.

so is anyone calculating there mpg using gps to monitor speed and distance and using an accurate way of measuring the fuel used, otherwise i dont think its gonna be that accurate.

[IanB2]

so is anyone calculating there mpg using gps to monitor speed and distance and using an accurate way of measuring the fuel used, otherwise i dont think its gonna be that accurate.

You can use your GPS to calculate the correction factor, as it will be consistant, and apply it to your fuel economy calculations.

[Surf01]

You can use your GPS to calculate the correction factor, as it will be consistant, and apply it to your fuel economy calculations.

Surely no need to do that as the error factor would be consistent therefore any calculations woudl give you the true mpg anyway.

[Surf_MoFo]

Surely no need to do that as the error factor would be consistent therefore any calculations woudl give you the true mpg anyway.

Well how can you get any accuracy when you base it on incorrect miles, the speed is not really important that's a guide as to your speeds but you need accurate measurement of fuel ie brimming and accurate miles travelled. Most cars are out a wee bit say 3mph but the surf is bad as I have seen 7mph of a difference from the gps but its lower at lower speeds.

[ROMEROTECH]

Surely no need to do that as the error factor would be consistent therefore any calculations woudl give you the true mpg anyway.

GPS is fine so long as you're on a flat and straight road with no elevation changes and you can keep your speed absolutely constant. Equally tyre pressures have to be correct so your tyres are the correct circumference to start with, and the faster you go the bigger the tyre circumference will become as centrifugal forces push and pull on your tyres, so you have to do it very slowly, but you'll still be guesstimating.

Normal navigation GPS takes readings at 1Hz-2Hz max, so not that accurate although still better than the speedo. Something like a RaceLogic Performance box takes a reading at 20Hz so you'd need something like the Performance box if you're intent on doing it by GPS to be more accurate.

Only way to be properly accurate is by a measuring wheel type instrument fixed to the outside of the vehicle. Then you cover a measured mile and then you can compare your speedo/odometer reading to an accurate reference measurement. Again, nice and slow.

Manufacturers across the world for years have designed into speedometers and rev counters a margin of error, so even though you think you're doing 40mph on the clock at 1500rpm the reality is much less than that. When i log speed on my Subaru using the laptop the reading i get is less than what i see on my speedo and rev counter even though it takes pulses from the same places the clocks do.

Personally i'll stick to using my clocks to work out mpg because at least that way the info i get is always from the same reference point and it's consistent despite the built in margin for error. Ultimately, it not going to be that many miles out so it's fine in the grand scheme of things.