I think that any engine, no matter who manufactures it, would complain at being driven, in your own words ‘hard’ and with approximately 25% oil in the sump, would expire.
Did you question where the 3 qts went?

 

No motor made by anybody is meant to be driven hard 3 quarts low on oil.

 

I think the value of a 2011 XF on 145k miles is so low it is pointless putting in even a used engine.

However, don't expect the other auto makes you're test driving to last any longer if you are a very hard driver. I suspect you'll be on the Audi/BMW/whatsit forum in a couple of years time complaining about a blown engine. Of course variety is the spice of life, so do enjoy your new car of whatever make you decide to buy. My optician drives an R8 and likes it a lot, but its a coupe so not suitable for you if you want 4 doors.

 

There is a Jaguar salvage yard in Sun Valley CA that does engine late model engine swaps. Not too far from you. He parts out a lot of late model Jags. I think he gives a 6 month guarantee. I know there are 2 Jaguar salvage yards in Sun Valley, and I can’t remember which one. Might be worth a call. Sometimes he advertises in the LA Craigslist.

 

I bought a used 51K 4.0 Jaguar engine (for an earlier S-Type) from this outfit a couple of years ago and was pleased with the service. Basically, they're brokers with wrecker contacts all over the country. Every sale comes with a Carfax to guarantee honesty on the mileage claim. Shipped it from New Jersey to California and with shipping it was cheaper and better than anything I could find locally.

Low Mileage Engines - Used Engines the Right Way