2012 XC60 D5 Auto... D or S for towing?
 

I have a 1400kg caravan and normally tow it in 'D' so as not to push the gearbox too hard but would it harm or be more beneficial in Sport mode 'S' on the geartronic box?

I had a D5 XC70 2012MY and towed a 1800kgs caravan with it. I always used D unless I wanted a bit more squirt on the hills. It is unlikley to bother the gearbox whichever you use and maybe not much difference in consumption either. I would just use whichever feels comfortable for the car. I found the best speed to tow at was around 57mph as it was in 6th gear and just under 2000 revs. At that speed on motorways /A road and dual carriageways it was happy to stay in 6th unless a steeper hill came along and then it would change down a couple of cogs if the hill was quite steep.

I always tow in D and only change into S for roundabouts and tricky junctions when a quicker getaway is needed.

I select manual for long downhills but it does not seem to make much difference but may save the brakes a bit.

I averaged 29 mpg on the computer the last time I towed which is probably 26 mpg.

My old caravan was 1500kg but have just changed to a 1650kg one but have not towed it on a long journey yet.

There's no reason to use S. The gearbox will work out there's a heavy van on the back, and will adjust its shiftpoints etc. accordingly (up and down).

Using S for setting off quickly is a good tip though as it avoids the need to really plant the accelerator to get a Sport mode that way... (or kickdown)

I tow 1751KG twin axle with my D5 and never use S mode for towing unless its a long downhill when there's a smidge of engine braking or when theres a series of roundabouts, which there are on some of my trips to Norfolk.

Doesn't seem to impact the fuel consumption, which is a consistent 22/23 mpg towing

Now I have a slightly different take on it to the drive it in "D" campus.

I have a 1500kg Caravan and have it in S for the majority of any long haul but return to D in slow moving towns/Suburbs, plus I am more often than not already in S for sudden terrain changes, be it severe uphill or downhill gradients, quick getaways at junctions and so on.

My actual main reasoning is that a faster spinning engine and transmission have lesser load stresses than one that is lugged in a higher gear lower engine rpm situation.

In fact my Volvo manual states in the towing advice section under the heading steep inclines, "Do not lock the automatic transmission in a higher gear than the engine "can cope with" - it is not always a good idea to drive at a high gear with low engine revolutions."

That said each to his or her own method....

I don’t think anyone would disagree in principle with that - but even left in D the gearbox will work out and select a suitable gear for the terrain, weight and commanded throttle. You will get a faster responses to increases in gradient whilst in S but the price of that will be increased fuel consumption overall.

What the manual is telling you is not to use geartronic to hold the gearbox in too high a gear for the conditions.

sounds good advice.

Iain