Magnet

Hello John,
I think you have answered your own question. You are considering a model with the suspension biased towards road holding and not comfort. I think the S Line attracts due to the additional features which come as the package, but the trade off is understandably a harsher ride. Don’t like a harsh ride? Best not to buy an S Line. As well as so called ‘sports suspension’ you will probably find it has low profile tyres, and maybe have the much harder sidewalls of run flats. If not, possibly XL. 
Kind regards,
Gareth. 

Thanks Ian,
So it’s maths time on a Monday morning then! 
3,000 miles at 60mpg uses 50 gals of fuel. 

If ( in caps) you would hope for an optimistic 10% improvement in mpg then you would save approx. 4.5 gals on your 3,000 mile round trip - or around £36 at current U.K. prices. 
Cost of chipping? Maths points to needing to travel approx. 8.5K  miles to recoup per £100 chipping cost. 
On-cost for increased insurance premiums -? This will obviously add to miles needed to be covered to reach the cost neutral point. 

Is a 10% increase realistically achievable? I think I would be pleasantly surprised if it was, and not too disappointed if it wasn’t. 
Your current 60mpg would be happy-days to most across the motoring spectrum. 
I think you’ve now got something to work with Ian.
Incidentally - average diesel cost/litre in S of Spain?
UK is around £1.80/ litre at the moment. 
Kind regards,
Gareth. 

Pending someone coming up with an answer to this Adrian - it is well worth considering having the auxiliary belt renewed at the same time. There have been reported incidences of these belts parting company, getting tangled up in crankshaft pulley, and putting sufficient rotational strain on it to cause the cambelt to jump teeth. 
On-cost should only be around the cost of the belt. 
Appreciating you have enough expense ahead of you, but if you think the cambelt should have been changed in 2018 (and again now in 2023) then one expense has been ‘saved’. 
Kind regards,
Gareth. 

Many thanks for the advice.
A bit of an update:- 
Had the ‘offender’ diagnosed as the centre left sensor, so now have a replacement on order, so fingers crossed. 
Diagnostics was done by an independent, when travelling to W.Wales. Incase it helps someone at some time, they are P.W. Motorsports at a village called Clunderwen, just off the St. Clears to Haverfordwest main road. 
I must say, I found them efficient and most helpful, and to me - the icing on the cake is that you can talk with them, rather than a service receptionist. Karol Gos runs the place, and he quickly gave me the Audi part number and advised not to pay Audi’s £160! but to buy an aftermarket one. All in all, a superb service in my book. I can’t vouch for their service work, but I was certainly impressed with the assistance I had. 
Well done Karol, and thank you for your help. 
So it will be bumper off to get at this one, and I hope for good luck. 
Many thanks again.
Kind regards,
Gareth.