S2 fuel consumption (20.7 mpg)

[zcacogp]

Chaps,

I have owned my S2 for around 6 months now, and have just calculated the fuel consumption on the last tank of juice.

304 miles was despatched since the tank was last brimmed, and brimming it again this evening took 56.82 litres. This equates to 12.49 gallons (imperial), and therefore 24.32mpg.

This is a fair mix of driving - both town slog (traffic jams et al) and some motorway work - some of it at moderate speed. I was making moderate progress for all of it, but not really thrashing it.

Two questions. One - are MPG calculations done in imperial gallons (if they are US gallons, the figure drops to about 20.2mpg!) And Two - does this sound about right for an S2?


Oli.
ETA: Just realised I have written the WRONG mpg in the thread title - sorry!

 

[TTM]

For the same kind of mixed driving mine returns 28 mpg.
It recently returned about 20 mpg on 120 mph+ drives on the Autobahn down Karlsruhe.

 

[Melv]

I used to get high twenties on mine.

You need to take off 10% to allow for speedo error............

 

[Diver944]

Thats sounds about right for mixed driving. Ours drops to under 20mpg if the entire tank is used just pootling back and forth across town to my wifes work two miles away, and we've had up to 33mpg on a long motorway cruise.

Incidentally your tank should hold 72 litres when full ( 500 miles range) so you are either filling it way,way before its really low or you are not filling it to the brim. The neck means that most pumps auto stop about 8 litres before its really full!

 

[zcacogp]

Guys,

Thanks. Sounds like mine is on the high-ish side, but nothing too frightening. I have been told that the car is running a little rich (once at MOT, once at a rolling road) and it may well be a function of this.

Melv - 10% error? You mean that the speedo is likely to show 10% higher speeds than reality, and also the odometer will record 10% more miles than you have actually covered?

Paul - 72 litres tank capacity? I filled it when the gauge was nearing 'empty' but not quite there (we had just been to Tesco, and had a 5p off per litre voucher, so felt the need to use it). However, I know that I have never managed to get the needle to show more more than 3/4 full on the gauge .... perhaps I am failing to get that last 8 litres into the tank!


Oli.

 

[carlmthompson]

ORIGINAL: Diver944


Incidentally your tank should hold 72 litres when full ( 500 miles range) so you are either filling it way,way before its really low or you are not filling it to the brim. The neck means that most pumps auto stop about 8 litres before its really full!

Is the S2 tank smaller than the Turbo? My book says 80 litres (72 +8 "reserve").

Incidentally, I've never put more than 60 litres in as the guage never reads full. Maybe it is clicking off 8 litres before it's full! Or maybe the guage is just lazy. Will try and put more in the next time I fill up.... which should be about February the rate I'm going!

Also for interest, I'm averaging 22.3 MPG over 2600 miles...... and two years! Not bad since every time it comes out is to give it a good blast.

 

[TTM]

ORIGINAL: carlmthompson
the guage never reads full

This is a common issue. The probe assembly costs about £80 at Porsche and takes 5 min to replace.

 

[Guest]

and also the odometer will record 10% more miles than you have actually covered?

Not the case. The speedo is a horribly innacurate thing, but the odometer should be pretty good as long as you've got the right size tyres on.

 

[Melv]

ORIGINAL: zcacogp


Melv - 10% error? You mean that the speedo is likely to show 10% higher speeds than reality, and also the odometer will record 10% more miles than you have actually covered?

Correct!!

ORIGINAL: Mikey

and also the odometer will record 10% more miles than you have actually covered?

Not the case. The speedo is a horribly innacurate thing, but the odometer should be pretty good as long as you've got the right size tyres on.

Mikey -they run off the same drive........

 

[Guest]

Yeah, they do.

Admittedly I haven't taken a 944 speedo to bits, so I could be wrong in this case, but the last one I looked at was basically a needle attached to a spring which pushed it anticlockwise, while a slipping clutch thingy drove it clockwise from the drive cable. This is mechanically pretty horrible, and can be innaccurate in a variety of different ways at different speeds. The odometer was (and is) a proper arrangement where each turn of the cable inner moved it on a specific amount. No slipping bits, just nice definite gear ratios. Only the diameter of your tyres will affect its accuracy.

Possibly the 944 has a nice accurate electronic speedo, in which case it won't be out by 10% anyway. But it's VDO kit from the 1980s, so I kinda doubt it.

 

[Diver944]

ORIGINAL: carlmthompson

My book says 80 litres (72 +8 "reserve").

Sorry you're absolutely right (I'd forgotten about the reserve)

The low fuel light will come on when the needle goes past the empty zone, at this point you still have 8 lites left and I've done nearly 40 miles before with this light burining a hole in my retina [] . You may want to take a fuel tank with you when you test your own light []

 

[DivineE]

Oh can I adda question to this thread! Was there an option to have a larger capacity fuel tank in the 944??? Reason I ask is that; most magazines quote the tank size as 60litres which would make sense in my old lux and the 86 turbo I'm now driving because I get about £60 of fuel in from the red, however in my 85 turbo and in the blue 944s I borrowed from John I could get about £78 in a tank when buying fuel at the same price??? How so?

Ben

p.s. I've found that engine condition seems to make a MASSIVE difference to fuel consumption because my 85turbo which burn't oil used to get about 18mpg on a long trip and my 86 turbo (which has a later 250turbo engine 'perhaps this also makes some difference?') returned about 32.5mpg over 230miles driving at between 75 and 120 with a few short bursts of hard acceleration to 140 included.

 

[zcacogp]

Helpful comments all, thanks for your input ...


Oli.

 

[Fen]

Tesco fuel will be part of the reason for the low economy (unless you are using "99"). Put proper 95RON in it and you'll se an improvement.

I think the tank got bigger throughout the model's life. Possibly the Turbo got the bigger one and it was added to the Lux later.

A top end rebuild made a huge difference to my Turbo's economy when I had it done a few years ago. I've had 460 miles from a tank in a 944, but I've never got to 500.

 

[zcacogp]

ORIGINAL: Fen

Tesco fuel will be part of the reason for the low economy (unless you are using "99"). Put proper 95RON in it and you'll se an improvement.

I guess you meant to write 'Put proper 99RON in it and you'll see an improvement'. Or are you talking about using 95RON from elsewhere in preference to Tesco's boggo stuff?

It's academic anyway, as I was using the 99RON stuff (and always do whenever I can.)


Oli.

 

[Fen]

I meant just put brand name 95RON in it, but if you're using 99 then that isn't going to cost you mpg.