Fuel Economy

My 98/R C2 Tiptronic with around 100,000 miles on the clock has up untill recently been averaging 22/25 mpg on the PCM unit on a combination or slow town, quick town and distance driving (27-30 on the motorway at restrained speeds!). No end of problems with it after the OPC did some relatively minor work on ir with resulted in several breakdowns and work being done under warranty. Cutting a long story short I have had new oxygen sensors replaced and a new Tiptronic gearbox (so, soooooo pleased I had the OPC warranty) and now the economy is at around 16/17mpg. Also seems to be idling a little lumpy but drives and pulls well and smoothly. Any thoughts? What are other people getting and does anyone know the 'official figures'? Thanks in advance. Rob

I reset my OBC three weeks ago and since then have done 3 motorway blasts to Brum and back (100 miles each way) and daily trips stop-start across town to work (7 miles each way). Computer is reading 22.6mpg. HTH. I would get a diagnostic check done by someone with a PST2. It would show if there are any pending problems which aren't at the point of triggering the 'check engine' light. (MAF related, for example). If you are anywhere near me get in touch as I might be able to help.

Hi Richard, I might pop into my OPC on Saturday morning as I have a long trip to Manchester over the weekend. Where are you based and thanks for your kind offer of help, what would you be able to do or advise? Thanks, Rob

Rob I'm in Maidenhead, Berks. I could run a diagnostic check for you.

Anyone else have some fuel economy figures they would care to share with me before my visit to OPC (or Richard [ ])? Thanks in advance.

I average between 22 and 27 per gallon. If I drive it hard for long periods I get about 18. If I drive it at asteady 70mph for 200 miles I can get 32 mpg! My car averaged 27 mpg on the 3000 mile Spain trip last year. Hopr this helps.

Motorway driving, mainly at ~ 80 (kmh obviously officer!) odd spurts higher as/when, computer says,.........27.2mpg. Hope it helps. D

I am averaging 24mpg with short and long journeys. On a run it will return 27/8 and on just short journeys then 20 Hope this is of use

15.4 MPG mostly town driving, but having recently done a 200 mile trip on motorways the 3 month average has moved up to 16.1 MPG.

Rob I would get this checked out as i do about 24/25 MPG unless i drive very hard. Do you know how many miles you get out of a full tank that may help to see if it is using more fuel than other members use. Phil

'99 cabrio C2 average 24/5 a gallon

Rob - you'll probably lose one or two mpg as yours is tiptronic.

Guys, Thanks forthe input. I was getting an average of 22-25 mpg until I recently had a string of problems originating with poor quality work at an OPC. All rectified under goodwill (as they caused the problem [&:]) and other stuff under warranty. The latest problem was oxygen sensors replaced and after that is when the MPG plummeted. I will pop into OPC and get them to check it out on Saturday and update this thead. Rodney, yours loks pretty low even with a heavy foot. I was getting 20+ around town in a spiritred fashion. Thanks again!

C4 Cab manual (3.4) Motorway runs averaging 80mph gives 29-32 mpg. General knocking around (mainly short journeys) gives 25-27 mpg with "entertaining" acceleration. Shell Optimax

[ ] After reading this thread, I tried very hard to raise my MPG for the day. During normal spirited driving around town and on dual carriageways, I was getting 13-15MPG. Driving very slowly, accelerating away from lights at a pedestrian speed I managed to get 20.6... How does everyone get these high figures? In my Boxster I was managing 16.7 (very few motorway miles)

For the last year I lived in Central London. I rarely did short journeys around town, but travelled regularly out through South London and cruised the full length of the M3 and M27 to Dorset. That represented about 90% of my driving and resulted in an average of 23.1 mpg. Now that I live in Surrey, with lots of windy bits, and a lot of short "convenience" journeys, the consumption has gone through the floor (as has my right foot obviously [ ])to something in the region of 15 mpg. Oh, and its a Tiptronic which, as Richard mentioned, is a little more thirsty than a traditional gear bag.

Hi Dave, Sorry don't know the answer as to why you're 2MPG different. To be honest, getting anywhere above 30MPH is great. I can only manage 16MPG!!!!! Has a lot to do with where I live (Traffic) and partly to do with me driving 'proactively' when I take it for a run in the country. Got a long trip to Manchester in a couple of weeks, so will see if I can better your figures and get back to you. I have a C2 3.6. Should be interesting. Just out of interest, what fuel are you using in the car?

Hi Dave, I've had 34 mpg out of my C4S on a steady run.... but I average anything between 27.5 to 30 mostly although I don't do much town driving... that does include a slightly higher than national limit on motorways tho'...... but only keeping up with everyone else! Guess I need to take the slippers off..... hth Paul PS - are you at Silverstone Classic this weekend?

Shell V-Power.

The best I've found at "motorway" speeds was 31mpg for a 3.4 Carrera 4 and 28mpg for the Turbo.

996C4S 3.6ltr 28.5mpg average over all situations including driving in France,Belgium and Germany - unrestricted[ ]

I usually get 32ish on a long run, and mid to late 20's on local runs. Never lower than 26. I tend to use Esso super unleaded. I believe you can use regular unleaded as the car has knock sensor though power will be down slightly.

Hello Dave, I have a 996 C2 Cabiolet 3.4 2001, and with spirited driving and an advanced driving course, got through a tank full in a day, the car is returning 29.8mpg, I know this as I have kept all my petrol receipts, sad I know, but this is an accurate average usage for one year. I know that if I drove my car to work, I would get 40mpg on the way in, and 12mpg on the way home, it's the lead foot syndrome. Regards Dodgy

Hmmm maybe my turbo was just unusually frugal before?! I used to get 32-35mpg reliably (every long journey I did) even got 37.2 driving for 1h 20 into london from Northants in traffic. I usually sit with the cruise control on at around 75 (gauge) and change at 3k rpms when warming the engine up on the 15min drive to the dual carrigeway. Now mapped I cant get it over 30mpg driving the exact same way. It averages 26 mpg if under 1hr on motorway, 28-29mpg if a long drive 1h 30+ I assumed this was because the turbos were spinning from below 3000rpm on light throttle where before you had to really poke the throttle to wake the turbos sub 3k. P.s. I always use v-power and if I arrive with flushed cheeks, a silly grin and orange glowing exhausts. The guage typically reads about 14mpg.

I can cruise at just over 90 and the boost gauge reads 0.0, so I expect that is your 'problem'. I can about 29mpg on the gauge if I cruise at 70, but life is too short for that. Mine's a Tip, so probably 2mpg worse than a manual.

I tend to reset the trip computer after every fill up and work out the millage that way. Its normally the same for each fill up, however just when i reset and pull out the petrol station im doing about 7 to the gallon lol. I think the computer is pretty acurate anyway so you could just use that.

I am as sad as Dave Green, I keep a spread sheet as well with the same information!!!!!!

ouch!!

From my experience 996's are pretty decent on fuel. My daily hack is a 2.5 V6, this gets around 28 changing at 2k all the time and doing the A road stretch at 65-70mph. The 996 can do 80 in sixth and return high 20's. Around town it's also comparible to most other mid sized engine saloons. Your 2mpg difference is very small on a run, it's going to be down to the road surface on the oposite side and inclines even though you may not notice - I can get 4 mpg more on the way home than on the way to work doing exactly the same speed driving in exactly the same way in both cars.

I think that these cars get quite good milage really, my last car was a 1.4 corsa and it only got 38 to the gallon, i think that when you have a big engine it doesnt struggle so much at high speeds like smaller cars do (if you watched that episode of top gear with the prius you'll know what i mean).

Very true - they aren't revving their nuts off + aerodynamics helps as well as the gearing

Yea thats the one. Stupid electric cars[ ]. IIRC when im doing the national speed limit[ ] in the 996 its only doing 3000 revs or so(i could be a coupleof hundred out on that tho).