Haldex controller for highway fuel economy?

[Ivo]

As I am driving mostly on highways lately, is there any real fuel economy if car is left on front wheel drive only during cruising at higher speeds?
Does anyone has some experience?

 

[<tuffty/>]

The haldex isn't really engaged when cruising... what are you asking exactly? there will still be transmission losses from the transfer box and prop plus a little drag from the rear even if you did pull the fuse... assuming thats what you are eluding to

<tuffty/>

 

[Ivo]

From what I know Haldex always transfers some torque on the rear wheels, something like 5%.
However Haldex controllers allows complete disabling of torque transmission to rear wheels, and car remains full FWD.

 

[tomjol]

Read some research a while ago which concluded that, even with transmission losses, having some torque going to the potentially-undriven axle was better for fuel economy than none at all and just having it drag along.

Unfortunately a bit of Googling has not thrown up a link...

 

[<tuffty/>]

The Hpa controller has an economy mode and also an off mode... So... $700 investment to gain maybe 5mpg (reported gains vary slightly)... a quick bit of maths suggest that assuming you are doing 30mpg, getting 35mpg would potentially save you £2.40 per tank based on a 62 litre refill etc so based on the original offer price of the unit at £550 (nearer £600 now) you would need to do over 200 tank fills to start seeing a return on investment...

Point is... if you are thinking of saving money from buying a controller then buy a diesel

<tuffty/>

 

[snowy]

Its 20% engagement unless braking, according to the haldex workshop manual I have

Pull the fuse and keep a log of the fuel economy

 

[Ivo]

Yes aftermarket controllers are pretty expensive. Point is that here in Bulgaria we have a guy that makes such controllers for pretty decent price. I am not spending 500 GBP to improve fuel economy with 5 MPG.
But to spend 100 GBP to get 5 MPG sounds good to me.
Anyway I have not bought this car to be economical, that's for sure, but if 5 MPG are reality I would get one.

 

[<tuffty/>]

Pull the fuse as snowy has said... cheapest and easiest way to see if its worth the effort/expense...

<tuffty/>

 

[JonnyDerv]

Can't see the point buying an S3 if you would want to disengage the haldex, if fuel economy is that important you might aswell of just bought a fwd A3.

Normally when pottering about I think it's 90:10 split at the front wheels, going up to max 60:40 if I remember right, it's practically fwd in normal driving anyway. Surely a haldex controller is just going to make the rear more active.

 

[<tuffty/>]

Depends on what controller you have... the HPA has selectable modes...

<tuffty/>

 

[snowy]

Lots of 4x4 vehicles have selectable 2WD/4WD modes for ecemony

If pulling the fuse does save $ for boring mway cruising, then you could wire a switch into dash

Much cheaper than getting the haldex remapped

Not sure I'd want to be permanently stuck with the economy diff map tbh

The idea of for the haldex on/off switch is something suggested by the Powertrack insert folks

 

[badger5]

i dont see how it would make the blindest difference
you are still dragging its **** and rear diff still churning away in the oil... being driven or dragged

haldex is not engaged on cruise as std

 

[Essexman]

If you pull the fuse you still have the dragged weight,

if you get a controller and just use it to fully turn the rear off then surely thats same difference as above

Also there must be 'inertia' & momentum thrown into the mix, (if you've got the weight then best to have a bit of drive to that weight than none at all) as said up there ^ somewhere

you can pick up a fwd 1.8t like mine for £400-600,

not bad mpg on motorways plus i have to say, as much as haldex quattro is good for people that use it regularly, i can still gun it down the lanes in the wet with my fwd & still keep it under controll, pulling away quickly not bad either,

the only need for more wheel drive is posibly awd 4wd 50/50 with a vcd on anything with more performance (4/5/600 bhp) like i think the golf R400 is having & what the Skyline r34 had ? just thinking out loud, but maybe i shouldnt lol

 

[<tuffty/>]

Buy a diesel

<tuffty/>

 

[snowy]

LPG

Narrower tyres - 205/50R17

 

[<tuffty/>]

...or accept you will get low MPG, fit a GT35, have 600hp and laugh manically at the ecomentalists as you drain the worlds resources whilst making your face ache from the permanent grin you will be sporting...

...and buy a small diesel as a daily so you can continue to afford to crush ecomentalists hopes and dreams every weekend

<tuffty/>

 

[limbo118118]

Smiles per gallon not miles per gallon thats my motto

 

[Jenno007]

...or accept you will get low MPG, fit a GT35, have 600hp and laugh manically at the ecomentalists as you drain the worlds resources whilst making your face ache from the permanent grin you will be sporting...

...and buy a small diesel as a daily so you can continue to afford to crush ecomentalists hopes and dreams every weekend

<tuffty/>

I think someone on this forum did something like that... But he needs a remap to get his 600bhp first

 

[basil brush]

There's more of a saving to be had by not filling your tank up to the top !
Do half fills each time and save many kilos also eat salad .
OR don't worry about it and have fun or buy a Prius .
Not sure why anyone who cares about MPG would by a 4wd turbo car !!!!