928 - Fuel Economy (1990 S4 - Catalyst)

neilbennet944 · **Posted:** Sun Jul 06, 2014 9:26 pm

Hi all,

Just got my S4 back from Paul Anderson on the 1st July, drives really well and also with a New MAF from John Speake (JDS) feels a great 928 to drive.

But, I want to drive it every day (60 miles of motorway - M23) and so far seems 23 MPG is the average over 300 miles.

Does anyone have any ideas on improving, like using Shell Vmax, driving at 60 MPH - What is the best MPH for MPG

I am really happy to daudle along if I can have my odd burst of fun.

Happy 928 Motoring

cheers

Neil

Brett928S2 · **Posted:** Sun Jul 06, 2014 11:12 pm

neilbennet944 wrote:

Hi all,

Just got my S4 back from Paul Anderson on the 1st July, drives really well and also with a New MAF from John Speake (JDS) feels a great 928 to drive.

But, I want to drive it every day (60 miles of motorway - M23) and so far seems 23 MPG is the average over 300 miles.

Does anyone have any ideas on improving, like using Shell Vmax, driving at 60 MPH - What is the best MPH for MPG

I am really happy to daudle along if I can have my odd burst of fun.

Happy 928 Motoring

cheers

Neil

Hi Neil

Wow ..23mpg... I am REALLY impressed...lol

My S2 is a daily driver and mostly used in town... and i get between 10 - 12 mpg...on a run (Motorway etc...) I would get around 18-19.... I have NEVER EVER managed 23...lol

If you really want to improve that mpg , you will need to drive at around 45 mph

All the best Brett

JasonGibson · **Posted:** Mon Jul 07, 2014 7:25 am

I used to use my old S2 as a daily drive.
23 sounds good to me

Usual rules apply, keep eyres inflated, windows closed and aircon off
I always used V Power but drove it hard

Waylander · **Posted:** Mon Jul 07, 2014 9:08 am

fit it with a 4.0 BMW diesel engine.... 23 is very impressive

stratfordshark · **Posted:** Mon Jul 07, 2014 11:32 am

23mpg would be typical overall figure for S4 - the Bosch injection is a sophisticated system and extracts good economy from a 5.0L V8. - much better than air-cooled flat 6! If you bring up the instantaneous mpg on the trip computer you can see what mpg results from what steady speed - if you lift off in top it will show 90mpg as idle switch engages!

V- power will make no difference as the management mapped for 95 Octane, and in fact the higher octane rated fuel has less energy per volume combusted which confounds expectations.

neilbennet944 · **Posted:** Mon Jul 07, 2014 5:41 pm

Hi All

Forgot to mention, but sure you know, my 928 S4 is an Auto

Once I have done 1000 miles I will know for sure if 23MPG is correct, the average MPG is now showing 24MPG

As my daily mileage is 58 on motorway and 2 on side road, I suppose my driving gets the best MPG possible

One interesting Question is , what speed does the Auto lock-up kick in, as too slow will upset this.

Seems best speed is good old 70MPH

---

Has anyone had SharkTune done as I am planning a visit to JDS

cheers

Neil

stratfordshark · **Posted:** Mon Jul 07, 2014 10:28 pm

neilbennet944 wrote:

Hi All

Forgot to mention, but sure you know, my 928 S4 is an Auto

Once I have done 1000 miles I will know for sure if 23MPG is correct, the average MPG is now showing 24MPG

As my daily mileage is 58 on motorway and 2 on side road, I suppose my driving gets the best MPG possible

One interesting Question is , what speed does the Auto lock-up kick in, as too slow will upset this.

Seems best speed is good old 70MPH

---

Has anyone had SharkTune done as I am planning a visit to JDS

cheers

Neil

Yes I wrote up visit to John Speake for shark tune here

viewtopic.php?f=27&t=4814

It's a must for S4 auto owners!

Brett928S2 · **Posted:** Mon Jul 07, 2014 11:47 pm

neilbennet944 wrote:

Hi All

Forgot to mention, but sure you know, my 928 S4 is an Auto

Once I have done 1000 miles I will know for sure if 23MPG is correct, the average MPG is now showing 24MPG

As my daily mileage is 58 on motorway and 2 on side road, I suppose my driving gets the best MPG possible

One interesting Question is , what speed does the Auto lock-up kick in, as too slow will upset this.

Seems best speed is good old 70MPH

---

Has anyone had SharkTune done as I am planning a visit to JDS

cheers

Neil

Hi NEIL

Not sure what you mean by "lock-up"... if you mean kick down, then it depends on the speed you are doing plus the amount of pressure you put on the loud pedal....

And if you are looking for ultimate economy...then 70 is WAY too high... think 35 to 50 max....

All the best Brett

potdog · **Posted:** Tue Jul 08, 2014 5:38 am

Hi Bret lock is at 55 M.P.H. ish on my S4 it is when the tork converter locks up to be 1/1 drive.

Brett928S2 · **Posted:** Tue Jul 08, 2014 8:36 am

potdog wrote:

Hi Bret lock is at 55 M.P.H. ish on my S4 it is when the tork converter locks up to be 1/1 drive.

Hi

You mean when it goes into 4th gear on the auto ?

If so there is no fixed figure.... you could get it into fourth at 20 mph on the overrun if you wished as an example....

If you mean when it goes into 4th under hard acceleration...thats 117 mph on most 4 speed auto boxes on a 928....

All the best Brett

neilbennet944 · **Posted:** Tue Jul 08, 2014 6:56 pm

Hi Brett,

Lock up is where the Torque Convertor is bypassed and there is direct drive from engine to wheels, without any slip.

This is an important step as without Lockup the automatic gearbox slip is costly and very wasteful

https://www.youtube.com/watch?v=jKh0lR8grZs

Keen to make sure I am always above this speed, depending on what Porsche has set

cheers

Neil

neilbennet944 · **Posted:** Tue Jul 08, 2014 9:27 pm

Seems to be a non-lockup gearbox

http://en.wikipedia.org/wiki/Mercedes-Benz_4G-Tronic_transmission

Any ideas !

Neil

Brett928S2 · **Posted:** Tue Jul 08, 2014 10:04 pm

neilbennet944 wrote:

Seems to be a non-lockup gearbox

http://en.wikipedia.org/wiki/Mercedes-Benz_4G-Tronic_transmission

Any ideas !

Neil

Hi Neil

Yup , lol...

Two choices...for economy...45 mph ALL the time...

Or just boot it and enjoy it.... its precisely why i use mine as a daily driver...and I really dont care about 12 mpg around town

All the best Brett

potdog · **Posted:** Wed Jul 09, 2014 5:24 am

HI all Mercedes do no make gearboxes they used Z/F gear boxes the Porsche 928 box is a H.P. 22

lightning · **Posted:** Wed Jul 09, 2014 7:27 am

My 928S4 did 20-25mpg, which l thought was good for such a large engine, with an automatic gearbox.

My Ferrari Mondial t did around 14mpg, driven the same as the Porsche. I now have a BMW Z3 3.0 and the economy is better (than the 928) but not much. The BMW official figure is 21mpg in urban driving, although l am actually getting about 25.

On a run l can get 35mpg. But it's a 3 litre engine with manual gearbox, where the Porsche was a 5 litre engine with automatic transmission.

Porsche Enthusiasts Club Forum

928 - Fuel Economy (1990 S4 - Catalyst)

Who is online