Petrol Light Chicken

[Lowtimer]

ORIGINAL: DivineE
Right I had a theory (when trying to persuade a friend to buy a turbo rather than an S2) that the turbo would be more efficient than an S2 if driven slowly because off boost its a smaller capacity engine. .

No chance, really, providing they are both in good order. The lower compression of the Turbo scuppers any advantage that it might have over the S2 based on the smaller engine: it also defeats the Turbo's gearing advantage. That said, I reckon I could crack 30 on the Turbo if I tried an economy run according to my normal rules, i.e. a week of my normal daily 45 mile each way commuter run, which is mostly country A roads and fast dual carriageways, driving as economically as possible but cruising at a true GPS-corrected 70 on the dual or motorway. That gives me 54 mpg in my BMW 320D.

Just calculated that if I had been able to get my Turbo up to the same MPG as awattam's S2, I would have been up to 529 miles: blimey!

 

[MRGT]

ORIGINAL: DivineE
the turbo would be more efficient than an S2 if driven slowly because off boost its a smaller capacity engine. I wonder if I can beat that on my trip to Wales in a few weeks.

Looking at my handbook which lists the figures for the 1987 8v, the S and the turbo (220):

at a constant 56 mph the 8v is 40.4mpg the S is 42.8mpg and the turbo 39.2mpg
at a constant 75 mph the 8v is32.5mpg, the S is 34.0 mpg and the turbo 32.1 mpg

I dont have the official figures for the S2 but expect it would be similar to the turbo's
From personnal experience on a long M'way run at 70 ish I get around 32-33, which is suprisingly fairly close to the book figure.
I once tried to match the constant 56 figure, but got bored after 10 mins []

Howard

 

[morris944s2john]

An 80l tank is:- 17.5975 gallons (UK) at 36mpg (which I have achieved in my S2 {at 65-just under 70mph} so it is a real world figure)

17.5975 x 36 = 633.51 miles on one tank.

It should be possible to go from my house in Margate to my sisters cottage on the north east coast of Scotland on one tank!

In fact, looking at the AA route finder,it should be possible to go from Margate to Inverness on one tank!!

I feel a Top Gear style challenge coming on []

 

[944Turbo]

I've done well over 400miles but I was in Belgium when a boost pipe split and drove it home off boost all the way, really struggle to stay off boost in normal driving - no point in having a turbo if its just a restriction!

 

[DivineE]

Some really interesting stuff coming out here, you can see in those mpg figures the advantage of the turbo's longer gearing just starting to come good once over 70 but 75 is probably a ceiling because after that even in WUF the turbo starts to assist even when cruising, meaning less vacuum, lovely throttle response when changing lanes on the motorway and terrible mpg figures

ORIGINAL: Lowtimer
my normal daily 45 mile each way commuter run, which is mostly country A roads and fast dual carriageways

When my daily commute for 6months was the same as that, leaving at 5-5.30 and arriving at 6-6.20 am my mpg was in single figures. My job satisfaction however was top notch as I smiled to myself all day about the drive to work and looked forward to the drive home.

 

[Fat Albert]

I am ecstatic if i get over 300 miles to a tankful in mine, I normally try and get 150 by half way and am lucky to get 280 miles most of the time.

I think if I bought some lighter shoes it may help......

 

[Sandspider]

For a long time I thought my low fuel light didn't work (as it didn't come on with the ignition on like the other warning lights). So, I never ran the car that low on petrol as I was expecting it to die at any second! Then, eventually, I discovered after a particularly long refusal to fill up, that it does work - oh, the joy! I've only had about 20 miles with the light on though.

Best calculated mpg figure in my lux is 32mpg (combined, but probably 2/3 motorway driving) and worst is 18mpg! (Leak in fuel return hose).

 

[Northern924]

Pity I did see the 2nd question when I'd just put £60 in, but with the trip not working its trying to remember what it was on

 

[tref]

65 miles with the reserve light on (I knew it would do 30, so headed for a known petrol station, only to find it shut) - I'll admit to coasting at every available opportunity (and watching the trip meter to see how much I had theoretically so gained - can't remember it now though), and not going above 50mph.

Overall, typically I get 400miles, on that ocassion 465miles. Most ever was 500 miles before the reserve light, which included 200 miles on the space saver, again, not going over 50 - yep, staying below 50 makes a big difference. Backing this up, and outstandingly perverse, my 944 does more to the gallon when towing my little box trailer than when solo.

 

[robwright]

ORIGINAL: tref

65 miles with the reserve light on (I knew it would do 30, so headed for a known petrol station, only to find it shut) - I'll admit to coasting at every available opportunity (and watching the trip meter to see how much I had theoretically so gained - can't remember it now though), and not going above 50mph.

Coasting actually uses more petrol. If the clutch is dipped then the engine must be supplied with fuel in order to keep itself turning over. If the take your foot off the accelerator and leave it in gear the engine consumes no fuel as the momentum of the car keeps the engine turning over until a point just prior to stalling when the ECU feels it has to step in. If you have an AFR you can actually see this happening. Foot off the pedal and the meter reads 20.9% O2. Dip the clutch and it goes back to reading normally.

 

[awattam]

ORIGINAL: robwright

ORIGINAL: tref

65 miles with the reserve light on (I knew it would do 30, so headed for a known petrol station, only to find it shut) - I'll admit to coasting at every available opportunity (and watching the trip meter to see how much I had theoretically so gained - can't remember it now though), and not going above 50mph.

Coasting actually uses more petrol. If the clutch is dipped then the engine must be supplied with fuel in order to keep itself turning over. If the take your foot off the accelerator and leave it in gear the engine consumes no fuel as the momentum of the car keeps the engine turning over until a point just prior to stalling when the ECU feels it has to step in. If you have an AFR you can actually see this happening. Foot off the pedal and the meter reads 20.9% O2. Dip the clutch and it goes back to reading normally.

True but I think the reduced distance that you are able to coast when in gear outweighs the advantage of not using the fuel it takes to idle the engine when in neutral.

 

[TheFiend]

Filled up on payday - it took 93 quids worth to fill it up as I was down in the yellow........

Going to see how long it lasts.... daily driver with a 40 mile round trip to work.

 

[DivineE]

ORIGINAL: TheFiend

Filled up on payday - it took 93 quids worth to fill it up as I was done in the yellow........

Does your S have the old shape dash then? I thought the S came after the 85.5 dash change over?

 

[Suffolk944]

I "inadvertantly" mananged to use a full tank today going from Ipswich to Oxfordshire and back. Don't want to even try and figure out what MPG that equates to...

 

[charlieb]

Three weeks ago I drove to the south of france - near Limoux to my mothers house for a holiday/driving trip.

On the way down we were travelling at a pretty constant 85-90 mph. I managed 430 on one tank. On the way back I zero'd out the tach and brimmed the car in limoux then travelled the longer way back - over the Millau bridge. I filled up at the 'centre de france', once again brimmed up. The tacho was reading 410- I did not stop again until we got off the train in folkestone when the petrol light finally flickered on - now showing 860 miles. So I reason I had done closer to 450 on the last tank/leg and coming out of paris up to calais we were probably north of the ton more often than not as we were racing the sat nav to get back for our allotted train.

Not bad going FWIW that was on 98RON (french put 10% ethanol in their 95RON e-10 which i was not prepared to try out) and wether it made a difference or not I had denzo iridium spark plugs fitted before we left.

Funniest thing I find about the fuel gauge is I would crack 250 miles and be an indicated above half a tank - then all of a sudden it would be between a quarter and a half about 50 miles later..