Wednesday 15th August 2018

Polestar offers rear-biased upgrade to AWD Volvos

A software change designed to make 90 series, 60 series and XC40s feel more dynamic? Sounds good to us

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So you know how Polestar is now a standalone performance brand creating its own models? Well, it turns out this doesn't mean it can't occasionally still have some fun with Volvos. The division's latest input into its parent company's regular cars comes in the form of new software designed to "optimise" all-wheel drive models "for more dynamic driving", which sounds good to us.

While no numbers have been released as of yet, Polestar said the optional software, available with 90 series, 60 series and XC40s in petrol and diesel forms from August, will send more torque to the rear axle. This should give the car more throttle adjustability and therefore make them more appealing to us lot.

Polestar's new optional software, which will cost £695 until the end of September and £835 from then on, is separate to its existing digital upgrade - the one that's already included on optional equipment lists. This software change quickens throttle response and gear change times, as well as boosting engine output to produce regular variants that rival the likes of BMW's M-fettled cars. The good news is cars already featuring the latter software upgrade get the new one for free, should their owners want it.

Looking further ahead, Polestar's influence on Volvo's range won't end here, because it'll also create more 'Polestar Engineered' models. It recently revealed an upgraded S60 Polestar Engineered that gained Ohlins dampers and Brembo brakes along with a boost for its electrified powertrain, which offers 415hp and 494b ft of torque, up from 400hp and 472b ft.

This all serves to keep the Polestar name burbling along before it really gets going. The firm's first standalone model, the 1, isn't due to reach roads in mid-2019, when it'll use a hybrid powertrain. Every other car after that will come in pure electric form, meaning pepped-up Volvos with Polestar upgrades could become the only way to enjoy this division's engineering talents with an internal combustion engine.

[RacerMike]

I assume when they say 'sending more torque to the rear' they actually mean 'locking the haldex centre coupling slightly earlier to send the same amount of torque to the rear wheels earlier than previously calibrated'.

There's absolutely no way they can send more than 50% of the total torque to the rear wheels unless they've magically found a way of changing the rear diff ratio with software....

Unfortunately, to get any actual rear bias from a Haldex or Twinster 'hang on' rear diff you need to run your Power Takeoff Unit at a physically higher ratio than the front diff. The only car that I believe actually does this currently is the Focus RS. Still....hats off to Polestar for fiddling around with some AWD cal stuff. It certainly can't hurt, and it's nice to see they have this freedom.

[RacerMike]

rockin said:

Given GM sold their "Northstar" V8 engine from 1991 onwards I can't help feeling Volvo's "Polestar" sounds tired straight out of the box.

Bit of a tenuous link there. Polestar have been around since 1996 as a separate company, and have a lot of history tuning Volvo’s and designing racing cars based on them, so it would be silly for them to change their name now. They are the defacto name in Volvo tuning in the same way AMG is for Merc.

[RacerMike]

Onehp said:

Exactly Mike, only way the rear can truly push from the rear is if they turn faster (obviously). Which is afaik never the case for Haldex cars so far...
The other myth the other way around is that Haldex won't drive to the rear untill the front wheels lose grip which is untrue for the later generations. So great traction, yes, truly intresting rear drive dynamics, not really...

If you run a ratio offset, you can make a Haldex car push more to the rear, but you’d lack the torque vectoring the Twinster offers by having two clutches rather than an actual diff. An ex colleague of mine actually made a Mk2 Focus RS with a Haldex 4wd system which did this. It was very fun by all accounts!

[RacerMike]

donkmeister said:

I was thinking this... I'm not aware of any transverse transaxle that can rear-bias simply due to the fact that the rear diff is driven by the same gear as the front diff.

The Focus RS is a genuine overspeed. It’s something in the range of 2% which is more than enough given that it leads to 2% extra slip on the rear axle. It has its limitations, but it does genuinely feel different to any transverse engined 4WD Car I’ve driven. I can regularly get power on oversteer out of roundabouts....