Volvo Polestar Upgrade

An auto will always return lower mpg than a manual and £650 will take quite a bit of mpg to recoup

I’d stick with it as it is. Those mpg figures sound acceptable to me.

You'd need to tell your insurance company if you had it chipped which might, or might not, affect your premium.

I had my Honda CRV re-chipped 2 years ago by a local specialist it cost £180.00

Honda CRV it should have a bosh EDC17 ecu which will be tricore protected we quote around 20-25bhp and 70nm on average 

What was more important to me was it gives me about 50 mpg per tank than what I got before the new chip.

I informed my insurance company and that modification cost peanuts

That was/ is usually the case with a slush box torque converter auto but improved fuel consumption is also one if the reasons why manufacturers are tending to go for automated manuals such as Volvos Geartronic auto box

Is the box an intelligent one likely to learn how to optimise itself whilst towing?

Its "normal" state is certain to be optimised for solo with the change points and lock ups placed to best suit that.

Slap the mass and drag of a caravan on the back, which gets 80 or 90% more mass, and greatly increased drag.

Therefore,  towing I would expect the torque converter will be working overtime, struggling to overcome the slip and benefit from "locking up", as intended in its target role. If it is intelligent it ought to improve during a long tow.

Have you experimented with using it in "sport" [assuming it has that feature], whilst towing?

I suspect from this, any chipping needs to target the gearbox's towing behaviour more than the engine's.

Volvos Geartronic is not an automated manual its a true torque converter just with the ability to drive in "manual" mode.  The latest and greatest true auto boxes from BMW etc are just as frugal as manuals not least because they are locked out most of the time.

Courtesy of Wikipedia -

"Geartronic is Volvo Cars' name for its manumatic transmission, similar to Porsche's Tiptronic. It is available in 4, 5, 6, and 8 speed models, and is controlled by a microprocessor. The microprocessor automatically shifts to the next gear if a forgetful user in manual mode red lines the engine. Manual shifting is allowed with the gear stick in the manual mode. The gear stick can also be used just like any other automatic gearbox, where the transmission will shift automatically."

yes a torque converter box - Volvos automated manual in the DSG sense was the Powershift now dropped in favour of the (much better) 8 speed auto/geartronic.

The OPs car will not be a powershift as the XC70 was never fitted with the D2 engine as far as I can remember.

Looks like Tinny has confirmed what I said .... It's an automated manual  😉

Nope - my Volvo has a geartronic gearbox and and I can assure you it's a torque converter as they always have been.  Only Powershift were auto "manuals" and derived from when Volvo used Ford engines.

Oh and Posches tip boxes are just TC boxes with paddles.  The auto manuals are the PDK boxes.