Fuel consumption and sticking rear brakes?

[oldtimer]

Hi , I'm new to 997S (3.8 engine) ownership, second owner of a 9000 mile car , but noticed that with my everyday non aggressive driving I get about 22mpg , whereas the 996tip (3.4 engine) it replaced did 26mpg driven same way. Is this normal ?

Second point I've noticed is that if left undriven for a few days , the brakes appear to glue up , so there is a distinct and noisy resistance to moving off for the first time . Looking at all 4 disks , 3 of 4 are smooth , but one of the rears is grooved. Before I traipse back to OPC , thought I'd check the forum . Any ideas?

 

[nsm3]

My 13,000 miler is exactly the same. I normally only get it out at weekends this time of year and the brakes make a noticeable crack when reversing out of the garage, worse if put away when damp/wet etc. It takes a good few stops for the brakes to scrub in and warm up before starting to perform. I posted almost the same query when I picked mine up 2 months ago!!

As for the grooving, it depends how bad it is but my rears don't look particularily pretty, unlike the fronts which are fairly smooth - so, probably no real problem?

And the consumption seems a good match for what I can return, although it does get better if I use it for commuting on the M5, rather than just the Sunday thrash around!

 

[oldtimer]

Thanks for the reinforcement !
I actually jacked the car up wheel by wheel to rotate them , and seemed OK ie brakes not obviously sticking . I used the jack from my other Porsche as I didn't get one with the 997 !
The best fuel consumption I get on a motorway is 29 mpg, and not a problem as the biggest cost of ownership will be depreciation as my 996 proved. Its worth it though , and the 997S is a great car .

 

[graham m]

John
22 is about right - mine has been up to 28 on 'a run' but averages between 21 - 23 mpg.
Cheers
Graham

 

[Bull996]

My 996 averages 14.2mpg [][]

 

[pvernham]

My 997s manual has averaged 19.5mpg over 8,000 miles, without much town driving to drag the average down.

If you're averaging over 20mpg, you're not trying hard enough [][]

 

[Ronnie C]

ORIGINAL: pvernham

My 997s manual has averaged 19.5mpg over 8,000 miles, without much town driving to drag the average down.

If you're averaging over 20mpg, you're not trying hard enough [][]

so so true !!!

I get 25.2 mpg on the motorways / long distance and 14.2 when I'm feeling a little playful.

 

[graham m]

Revised figure! Just done a bit of track day at Oulton and achived 12 mpg! Must try harder next time and get down to single figures!
GPM

 

[sidicks]

Well my current average is around 24mpg, and my wife managed 29.5mpg on a trip down to Bognor yesterday.

To be fair, the car has only done 310miles and is still being run in so I do have a good excuse.

I promise to get down into the 'teens once the running-in period is complete !!

Sidicks

 

[Guest]

you should be aiming at around 12/14 mpg, otherwise you should get a Ford Mondeaooooo[]

 

[oldtimer]

Interested to hear that you've ventured onto the track with it Graham., thought you were worried about stone chips...[]
How did the brakes/tyres stand up to it ? I gave a 997S driver a ride(untimed) round Donington in the 964RS at last years PCGB trackday , and he then gave me a ride round in his 997S , with the chrono and PASM on. Interesting back to back comparison . The 964RS felt faster but it was hard work ! Maybe when I get used to driving the 997S fast ,as others here are suggesting , I'll go back to Donny in it , Oultons bit too narrow for me []

 

[Guest]

ORIGINAL: oldtimer



Second point I've noticed is that if left undriven for a few days , the brakes appear to glue up , so there is a distinct and noisy resistance to moving off for the first time . Looking at all 4 disks , 3 of 4 are smooth , but one of the rears is grooved.

May help if you leave the handbrake off and just leave the car in gear if leaving it for a few days (obviously only if the car won't roll off etc) as this will prevent the handbrake pads binding to the disk.

 

[graham m]

It was so wet on Friday that I doubt I suffered to much tyre wear - the brakes and PASM etc worked wonders. Ran on Sport Setting and had a fantastic time. No evidence of collecting stone chips as I each time I caught cars up the marshalls 'Blue Flagged' them out of my way[]. Even Neil in his 993TT couldn't stay with me[] - maybe I just left my sensible head at home on Friday[&:]
GPM

 

[nsm3]

I'm pretty sure when I posted on this subject in January, someone indicated that the handbrake doesn't act directly on the rear disks but inboard of the wheels, perhaps on an output shaft?

I haven't a clue if this is correct, but I still leave the car in neutral and with the handbrake off (luckily my garage floor is dead flat!) to stop it all binding up.

 

[oldtimer]

Thanks for the info, nsm3.
FWIW , I never put the handbrake on when I park up at home anyway as I am aware of how it can fuse itself to the brake surface.
This month I left the car for 8 days and when I came to use it , it needed an almighty shove on the accelerator to break the 'stiction' and get it moving...then got some grinding noises for first few applications of footbrake . I don't think the latter is unusual as the 996 used to do same. Will discuss with OPC .