Fuel economy and range

[Jarcy]

After two years of ownership, I thought I'd find out what fuel economy I am achieving.
I'm concerned that my range is poor, and I'm having to fill up frequently.
My engine is standard and has just been serviced.

So, after a hoon on full-beans, I achieved 18mpg.
Cruise home at swift motorway speeds, I achieved 25mpg.
Extrapolating, I expect I'm getting 8-10mpg on track, but haven't measured accurately.

OK, so not too bad, and as I'd expect.
So why am I filling up after 150 miles?
I fill up when the needle reaches the 1/4 mark on the gauge, as per the manual, but after a recent fill up I noted that this was 38 litres.
Our standard tanks are 70 litres AFAIK, so I conclude that the 1/4 mark still has almost half a tank full left.

Two questions:
- Am I being over cautious and filling too early? Could I run to the zero point on the gauge?
- What mpg are you achieving following power upgrades? I'm considering going for 425-450bhp next year, but keep the car's nice manners and a respectable range.

[macky17]

I'm still unclear as to the 1/4 full thing. I've heard people say that you can run the needle to empty on later cars as that actually indicates 1/4 full but it's not something I'm in a hurry to try - especially as my fuel pump gets noticeably louder as you drop into that last quarter...

[kenloen]

Went past the last garage heading into Rouen on way to leman the other year with the needle on 0. Another 30 miles further on we were stuck in heavy traffic as a bridge was out and I thought I was in trouble, the needle wasn't moving off the stop. Eventually when filling, the tank was only 3/4 empty. Averaged 28mpg that journey mainly cruising at 80 - 90.

[AMG Merc]

You're about right. Av. 200 mile per tankful - so you're filling up early, as we all do. No problem.

My latest addition has a 100 litre tank

[mr.man]

I think you will find the tank is 60 litres. I ran my GTO 3 from new for ten years and 30000 miles without running out of petrol and nearly always let the gauge drop to zero. This varied from 220 miles to 250 miles on the trip meter. The telling factor is how much fuel you put in subtracted from 60 litres. Mine was usually about 42 - 45 litres so a good safety margin was left in the tank in reserve. The 1/4 full warning only applied to track driving. We were sent a letter from the factory explaining the risk.

[Jarcy]

mr.man said:

I think you will find the tank is 60 litres.

I took the data from here, but willing to be corrected:
http://www.carfolio.com/specifications/models/car/...

The pro-alloy replacement tank states that it's just 55 litres, so maybe 60 litres for a standard tank is realistic.

[andygtt]

Standard tank is just over 60 litres but due to the design you can only use 55 Litres (having cut the tank apart and measured accurately)

My new tank is almost identical dimensions but due to its design I can use all the fuel in the tank safely (I have swirl pot and lifter in the tanks) and I have put little over 61litres in a drive in drive out fuel visit were I knew I was low on fuel

When the car was standard I used to get over 300miles to a tank and an average 30mpg and never ran out of fuel in it when it had the stock tank (I have with the new one as the fuel gauge used to lie and caught me out a few times).


I get similar mpg to you now and do 200-220 miles between fill ups but then I can use more of the fuel in the tanks, I recon I would be filling up at 150miles if i still had stock tank... what spec are you running?

[verba1]

[quote=Jarcy]

I fill up when the needle reaches the 1/4 mark on the gauge, as per the manual, but after a recent fill up I noted that this was 38 litres.
Our standard tanks are 70 litres AFAIK, so I conclude that the 1/4 mark still has almost half a tank full left.


I filled up my 3r from around the quarter mark and stuck in 30 litres and it was full .
My manual says tank takes 60 litres .

[Chapppers]

What happens if you run out? Bad things? It not I'll grab a can of fuel and go see how far one can really go on a full tank.

[andygtt]

If you have decent fuel filters the worst thats likely to happen is you destroy you fuel pump... with mine I simply had to replace the fuel filter as the dregs in the bottom of the tank cog'd it up.

I once filled up in Dover got the ferry and drove to Amsterdam, then drove around Amsterdam for a week in the evenings after work before filling up for the drive home (over 300 miles)... they can be very economical if driven as an everyday car rather than a toy.