I don't go that far often in my RRS but as my XC70 in for a new gearbox, needed to drive it to Kent (with its fresh MOT!). It drives fine until you're doing M'way speeds and then every time you press on the accelerator it seems to grumble and the wheel starts to shake. There's also obviously a point where its shaking and reluctant to go any faster and the noise is quite loud. I'd say it was sluggish. The other thing was even when keeping a steady speed, you could see the rev counter was acting like an old style one - ie not keeping to a given rev but fluctuating around 50/100rpm. No engine faults that I can see on IID

Aerodynamics undoubtedly not helped by the light bar but not that badly

Sounds like a torque converter issue

I concur with DM, definitely sounds like the torque converter is giving up the ghost. 2011 RRS HSE Luxury 3.0 TDV6 Fuji White on Ebony/Ivory
Born and raised in So Cal. Moved to the UK in 2018 for a few years. Now in Poland and looking at moving back to the UK.

Do naughty things to a duck...

Thank you. I take it that's either a new torque converter or gearbox? Which I imagine is a body off job again?

Not body off (thankfully!) but not cheap either

We use a shop that opens the converters and rebuilds them.

It is a bear of a job though, prop shafts out, cross member out, starter out, move the fuel cooler, exhaust preferably out, transfer case off, transmission out. May as well do the filter conversion and mechatronic seals while in there. 2011 RRS HSE Luxury 3.0 TDV6 Fuji White on Ebony/Ivory
Born and raised in So Cal. Moved to the UK in 2018 for a few years. Now in Poland and looking at moving back to the UK.

My mechanic will be pleased

Thanks guys

I used Bristol Transmissions for a new TC on my old TDV8. Turned out that it needed a bit more than that as the output spline was worn - they said they would only do the TC if they also did the splines in the gearbox and the transfer case (input shaft also worn). Fair enough. But you have to take the insides out of the gearbox to get to the output spline. So they ended up doing a gearbox refurb, effectively, and they put a new chain in the transfer box. That ended well up over a grand, as you might imagine. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

Told my mate about the grumbly gearbox and he got all excited and said try Lubeguard Shutterfixx. I was a bit skeptical to start with but for a few quid worth seeing what happened. Duly turned up, popped the hose off the cooler, extracted 60ml of dirty brown (but not smelly) transmission fluid and dropped this stuff in.
I won't say its all cured but it is noticeably better! The hunting rev counter has gone and its smoother on acceleration. Still a bit sluggish once up to motorway speed but much improved.
From what mate said, as the fluid gets old the plates on the torque converter get glazed and this stuff removes that.
Seeing what so far has happened, I'm going to flush the transmission and whack some more of this stuff in. If it gets even better and drivable, then brilliant, if it continues to grumble, then I'll change the TC.

We talk about "it needs a new torque converter" but it's really the lock-up clutch that causes the issue. Perhaps we need to remember that when looking at the problem. It's worth remembering that these tubes of stuff don't really solve the problem, they just delay the inevitable.

(You can get other issues resulting from other clutch packs (of which there are several) in the gearbox too, but they are, thankfully, less common I think.) 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed