Actually I cross shopped between these cars (plus the XJ) and ended up with the GC, for the following reasons:
1) We used to run a few cars as a family, allowing me to have a 2 seater sports car plus a saloon for practicality, plus a hatch. But we've been driving less and less, we all spend alot of time out of the country, moved right next to a town centre to make our lives easier getting in and out of work, etc. Thats culminated in us barely requiring two cars, let alone three and only putting 5/6k miles on those two aswell.
2) I fall smack bang within the target market for the 4 door "coupe" sector. I need some of the practicality of a saloon, but am able to forego a fully practical saloon in exchange for aesthetics. I still want a car that makes me want to turn back and take a second look at it, that makes me smile when I walk out of the door in the morning, that I haven't become numb to due to over exposure. I live in London and unfortunately a 5/E class/etc all fall within that last bracket, bolting on some M/AMG/S paraphernalia doesn't change that.
3) In the UK the MSRP has little or no bearing on what you pay for a car. Buy it cash and there are almost always significant discounts available. Buy on lease and manufacturers often have incentives meaning the MSRP can often bare little relation to your payments. Buy as a company car and the emissions of the vehicle can vastly out weigh the MSRP when calculating what the car will cost you. In all there was about 10-15% between the cars (640d M sport GC, A7 BiTurbo Diesel, CLS Diesel sport, XJ 3.0 Diesel portfolio), less if you factor their prices when they were year 1 models (the GC still holds a slight premium as its barely 6 month old model in the UK).
4) Factor in depreciation (the biggest hit if you're not buying on finance), insurance, taxes, etc and that price differential becomes less and less significant. This is not the budget sector, i'm already paying a hefty premium over the saloon equivalent for aesthetics, something different, something I wont find around every corner, in every car park, etc. Therefore 10% or even 20% is not going to make one suddenly think "damn I prefer the GC, or Panamera, but its more expensive so I'll take the car I don't like quite as much". Being in the market for these cars already means you've made the decision to compromise on value, if not you'd be in the market for the saloon equivalents.
So why did I pick the GC from the bunch:
1) Aesthetics, inside and out it was the one we all preferred.
2) It and the XJ were the best drives (I prefer RWD generally, Audi is FWD or 4WD only).
3) Family insisted on 5 seats. That ruled the CLS out. The GC just squeezed in, as we'd rarely need the 5th seat, so the compromised 5th seat was tolerable. The fact everyone preferred it anyway also helped
4) The XJ just felt a little old for us (we're in our mid 30's). I was also hesitant to pick it over the German trio, despite Jaguars reputation having improved significantly since the XF.
5) Both the CLS and Audi are likely to be more common in the UK. There is a far bigger spread in pricing across the ranges of the two cars. For example the 2.8l FWD SE A7 is priced in 3 Series territory. I'm already starting to see them more regularly then I'd expected. If you refer back to point 2 at the beginning of my now long post you'll see that somewhat defeats the purpose for which I'm paying a premium to begin with
The difference in price simply wasn't a major factor. I've already reconciled myself to taking a massive kicking in depreciation and paying more over the saloon equivalent. I would imagine anyone else seriously in the market at this price level would have done the same. You're going to buy based on what you like, not 10-15% price difference either way, particularly for niche models like 4 door "coupes".
P.S. "coupes" is in quotes as despite what manufacturers tell us, they are not "coupes" :/