Max fuel economy vs DPF

[Billy Beatnik]

Hi 

Dont know if this has been asked before, probably has, but I do a fair bit of motorway mileage and was wondering at what speed I get maximum fuel economy on the motorway, while also looking after the DPF’s needs.

Thanks

Ste

[Jon Hyde]

Hi Steven,

I've had mu 3.0d V6 XF-S for just over a year since retiring (2011, 66K miles now). I find that on long motorway cruises, loaded with luggage, and with cruise control set at 77mph, I get about 47mpg. That seems very good to me, but if I hit some bendy stuff and go for sport mode, the fun increases in line with consumption (has been down to 18mpg, but still, so much fun!). So far, (fingers crossed!) no DPF issues, but I do use premium diesel and add Millers Oil additive every fill-up.

I think it's about enjoying the drive though, whatever the cost!

Cheers,

Jon

[JOE-DOT-COM]

hi

both are completely opposite driving styles

dpf regen needs higher revs to get the dpf hot to burn off all the soot

economy need low revs to get the best miles per gallon

so you can't win, if you want mpg then your blocking up the dpf, if you want to regen or clear the dpf the mpg's go out the window

give the car to a young lad and youll never get issues with dpf and there also not bothered about mpg's

drive it like Miss Daisy and your always going to have issues with dpf

cheers

Joe

[Jon Hyde]

Hi Joe,

Completely agree! I regularly wring its neck, but when off to the in-laws in Ireland, I have a speed limiter in the passenger seat! So far, I find a mix of cruising n bruising works well. There isn't a week without dialling 'S' for a bit of fun.

Cheers,
Jon

[PeteL]

Hi Jon, I have a similar limiter in mine, extremely reliable too :-)) 

Joe, I get in and on every trip I give it a good heavy right foot for at least part of every journey. Mine is only 3 years old and 26K on the clock. I don’t know how it was driven before I got it so I’ve got some snake Oil of some description to put in tomorrow to give it preventative maintenance. I’ve driven diesels for the last 20 years and because of the mileage I used to do I’ve always used supermarket fuel and never had a problem. Hence I give it some welly on every trip now I’ve been put out to pasture. I don’t know if I’ve helped at all but my mpg is what it is.

cheers for now.

Pete

[Billy Beatnik]

Thanks guys. I would like to add that I usually do about 75mph on the motorway, so it’s not like I tootle along at 50mph! I was just wondering if 75mph and doing a fair few motorway miles would keep the DPF happy?

[JOE-DOT-COM]

Hi

Its not the speed, its the revs you need, the DPF is like a filter, thats blocks up and the only way to clear it is heat, higher than normal revs get the dpf hotter and allow to burn the soot off

at 70mph in my S-type R in sixth gear would barely be doing just over a 1000rpm

select a lower gear and keep the revs up a bit more, for 15 mins or so just to get the dpf up to temp

cheers

Joe

 

[Billy Beatnik]

Thanks Joe

[PeteL]

I took mine for a good run yesterday after putting in the snake Oil. I ran it for 20 minutes at 3000 rpm purely as preventative maintenance. Hopefully it will have cleaned any soot out that has accumulated. I’ll update if I notice any difference in power or mpg

Pete