Fuel economy

mjheathcote · May 8, 2016

Didn't buy it for fuel economy, let's get that straight first!
Just interesting as I don't use mine for any long journeys, but early this morning was travelling up the A1M and decided to pin it at 70mph on cruise, as it was a little misty and I was not in a hurry.
Anyway the on board trip kept swapping between 24 and 24.7 mpg for the whole journey.
So saying on a long tour, when the speed can be kept pretty constant, what is the optimum cruising speed and best possible mpg achievable?
I watched a Harry's Garage youtube video yesterday and he was driving a new 500+bhp Jag fully ladened up down to the Alps and he got over 30 mpg, so why can't ours achieve anything like that? what's changed tech wise to achieve power and economy?

drewf · May 8, 2016

Considerably more tech on the newer engines. The V12 Merc I had would easily manage 26 mpg, despite being a huge engine - it shut down half the engine when on part throttle, so adding significantly to the fuel economy.

alfatwo · May 8, 2016

drewf said:
Considerably more tech on the newer engines. The V12 Merc I had would easily manage 26 mpg, despite being a huge engine - it shut down half the engine when on part throttle, so adding significantly to the fuel economy.

Its all clever stuff, they run 4 or 5 cylinders most of the time when your just rolling along. You don't need more than 50hp when your cruising!

Dave

safrane · May 8, 2016

24/25 is about as good as you can get...done a long trip across France at a steady 60 and that was the best I could get.

D Walker · May 8, 2016

I have never seen better than 19.1 on mine, that was on trip round Scotland, where in real terms it sat at 18.4!

Lozzingers · May 8, 2016

I think I averaged about 22 ish over the 6 months I owned my granturismo. I did get 29.9mpg (according to computer) on a trip from Poole to Heathrow! Cruising at about 70 +10x (where x is anything from 0 - 1 mph). It was at 27.2mpg prior to 20 miles of 50mph on the M3. Once up at speed these cars are quite OK, as are low drag etc, just getting 2 tonnes up to speed in 5.2 seconds uses rather a lot

Blooming brilliant cars, miss it!

allandwf · May 8, 2016

If mine cruises at around 90, where allowed, this seems to be its optimum and gets around 25.

Wack61 · May 8, 2016

I used to slipstream coaches in my van because they do 65 but you'd look a bit of a plonker doing it in a maserati

when i was doing my round trip to portsmouth I stuck to 60 and got it up to 25-26 but it was proper boring

TridentTested · May 8, 2016

I've seen 26 mpg on a quiet run from Manchester to London, once. 22 is normal on long runs.

If it puts it in perspective, after 16 years of ownership I've finally got around to measuring my motorbike's consumption and am surprised to see it is a poor 38 mpg. That makes the two tonne QP amazingly parsimonious. Or at least that's how my man maths views it.

Jkulin · May 9, 2016

I regularly get 28+ on the QP when on the motorway and that includes some fast bursts.

Around town I get anything from 14 - 20

daverichardson · May 9, 2016

Jkulin said:
I regularly get 28+ on the QP when on the motorway and that includes some fast bursts.

Around town I get anything from 14 - 20

Same here with my QP Exec

P R · May 9, 2016

Are we derv-erts allowed to participate in this thread?!

CatmanV2 · May 9, 2016

P R said:
Are we derv-erts allowed to participate in this thread?!

No. You're sick and twisted!

560 miles from Â£60 of Satan sperm in the A8. *Disgusting*

C

GeoffCapes · May 9, 2016

I've got over 750 miles from a tank in the Merc. That was boring as well.

If you run it at around 100mph on cruise control (in Germany obviously) you get around 570miles from a tank.

As for the Maser, I before my breakdown, I calculated that I got about 12 miles to the gallon from the last tank.

P R · May 9, 2016

Well ok, mine has seen around 51mpg on the computer, which would equate to around 47 on a run. Generally I get around 40 with a mix of town / extra urban on my commute.

zagatoes30 · May 9, 2016

What is the fuel economy you are all going on about my process is as follows

1. Fill Tank
2. Drive
3. Go to Step 1

Nice and simple

Contigo · May 9, 2016

I never ever look, really don't see the point. If I want an economical car I'd buy a diesel and they are ****!

drewf · May 9, 2016

Contigo said:
I never ever look, really don't see the point. If I want an economical car I'd buy a diesel and they are ****!

It's useful to know for other reasons than just how 'economical' it is. For instance, if the mpg changes dramatically, either up or down, then there's something wrong and you can investigate before it becomes an expensive problem. I've never seen anything like 28mpg on my QP though, even with Susie driving

Contigo · May 9, 2016

drewf said:
It's useful to know for other reasons than just how 'economical' it is. For instance, if the mpg changes dramatically, either up or down, then there's something wrong and you can investigate before it becomes an expensive problem. I've never seen anything like 28mpg on my QP though, even with Susie driving

With a Maserati there will be plenty of other warnings!

drewf · May 9, 2016

Contigo said:
With a Maserati there will be plenty of other warnings!

True enough!

I do like to know roughly what the car is doing though. I once ran out of fuel in a V8 Range Rover, which had about 15mpg at sea-level, but 6mpg in the Alps. Distance from low fuel light coming on to car dying was less than 10 miles, at 1am on a Sunday. Luckily, it died just as I turned into the destination driveway, and the next morning I managed to beg a few litres of fuel from a farmer which got me to a petrol station.

Fuel economy

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