911 (997) C4S fuel tank question

sidicks · Aug 30, 2010

Am currently in Yorkshire for a wedding which has provided a nice opportunity (280 miles each way) to run in the new Bridgestones referred to in a different post!!

I did have an unfortunate incident where I nearly ran out of petrol as 3 garages listed on the Sat Nav turned out not to be there (probably due to the amount of new construction on the A1(M) these were temporarily closed down).

With zero miles already showing on the trip computer, we then used the Sat Nav POI to head along the A61 to the nearest petrol station which was then closed!!! By now I was really panicking, but we asked a local who directed us towards the local Tesco garage, a further 2-3 miles away.

By this point I was wondering when the car would finally stop, and therefore how long a walk I faced, but we made it all the way to the garage without any spluttering which was a welcome relief. I sensibly decided that this wasn't the time to be snobbish about only using Shell V-Power, and Tesco 95 was considered more than adequate!!!

I manged to fit nearly 63 litres in the tank, the most I've ever had to put in the car.

When my wife read the drivers manual, it said that the fuel tank is 56 litres, with a 10 litre reserve tank. Does this mean that the trip computer bases your remaining mileage on the main tank only, so once you hit zero miles, in practice you have 10 litres spare which should be enough for 40+ miles??

I don't plan to cut things this fine again, but it would be good to know what the real situation is!!

I believe that due to the 4WD, the fuel tank is a slightly different shape to that in the C2S, but not sure if this makes any difference to the reserve tank?

Thanks
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Sidicks

garyw · Aug 30, 2010

ORIGINAL: sidicks
When my wife read the drivers manual,

Sorry but I nearly spat my tea out when I read that!!

I can't answer your question on where the tank reads from for the trip, as luckily I've never had it that close.. sure I've seen the -- in the remaining display which normally goes like that after 10 miles remaining.

garyw

Porrohman · Aug 31, 2010

Whilst I would not want to try it I think most car manufacturers build in a large margin for error on their trip computers. Remember Clarkson driving the A8 back from a return trip to Edinburgh with the trip reading zero miles 40 odd miles north of London and a similar thing when he drove the Jag to Blackpool only to find that he had over a 100 miles of fuel left in the tank when he got there. I have done 40 odd miles in my Mercedes on zero. One has to presume that the reserve fuel is not taken into account but I am only guessing.

I have got caught out by garages being closed and try not to sail too close to the wind although we all hate stopping for petrol!

dilloncallum · Sep 1, 2010

I had a bet with a friend of mine some time ago.

He said that there was no way I could go from his house in France (point a) to a point in the country (point b) where we had a meeting (which was 300 miles away) in 3 hours.

"Ive got a 911" I said. The bet was for the sum of £5.00

We left at 6.00am and the roads were empty.

I was assured that I would not get 'pulled' by going through the toll roads too quickly, but I was flashed by the speed cameras on the way.

The computer said that I had 330 miles when we started (I filled up the night before and the petrol station was pretty much one mile from the house).

Travelling at speeds up to 160, I watched the miles to empty thinking there would be room for error (and I did not want to waist time stopping for fuel).

When the computer said 0 (which I had never seen before) it was only a matter of 30 seconds before the car lost power and all the dash lights came on and we cruised to a stop.

The breakdown man came an hour and an half later and spoke good English. He asked what the problem was and I told him that we had ran out of fuel (the shame of it). He charged me about £40.00 for a can and then told me that the petrol station was over the brow of the hill in front of where I had stopped (it would have taken me all of 5 mins to walk). The shame!

The point is; The computer does work and work well if you are travelling at an average speed.

It turns out that the entire journey was 312 miles from point a to b and we were 3 miles from the finish when I ran out of fuel.

Porsche said that the engine management stops any damage to the engine and the car has run well ever since (this was some years ago) with no problems.

I'm sure the 997 computer will be better than that of the 996, and looking on the bright side, the consumption of the car at those speeds is pretty good (but it could do with having a bigger tank). The orginal 330 miles shown at the start was pretty accurate; but I would not recommend to try the range for yourself.