Thanks! I have it narrowed down to the Jag, a 2001 Audi A6
4dr quattro AWD Auto 2.7L 6-cylinder, or a 2001 BMW 530iA 4dr 3L 6-cylinder automatic.
All under $7,000. But the Jag is cheaper..so, we'll have to see.
If the Audi is the 2.7 twinturbo V6, avoid it. Great engine, but a mechanics nightmare. Also as Spectre said, Audi has a history of bad automatic gearboxes, which is why mine is manual. I would not consider the Audi in this case and this is coming from someone who has one, though not an A6.
I have no idea what sort of service and customer care you get for BMWs that side of the Atlantic, but as a car, E39s made after 9/1998 are among the best cars Germany has ever produced. 9/98 is the critical number, because cars made after that received a mechanical facelift: new and improved VANOS system and many electrical glitches were fixed and never heard from again so on that front of the 5-series I disagree with Spectre and so do most of the BMW enthusiasts.
The E39 5-series had very little faults to begin with, but the most important were ABS sensors, air flow sensors and pixel faults in the dash. Water pumps have also been known to cause trouble. Other than that, not many things go wrong in the E39. Rust is not an issue: if an E39 does have rust, it will be found on the lower edge of the bootlid and behind the fuel filler flap.
Transmissions are not weak like they are in Audis but they do have a rather annoying feature: they can go 200.000 miles without an oil change, not missing a beat. But when you do change the oil, they might blow up within the first 500 miles. Nobody knows why this is, but BMW transmissions have been known to do that often enough to list it as a typical fault. Manual ones don't have issues at all.
The E39 with 3-liter straight six was regarded (and by many still is) the best car in the world. The engine is quite bulletproof and I already listed the few typical things wrong with BMWs.
It all comes down to two things really: if the service and prices are as horrible as Spectre says, get the Jaguar. Second of all it's about what you want and like.
As someone who drives an Audi and almost bought an E39 5-series, I would say go for the Jag. I believe the E39 deserves a manual gearbox and a lot of the cars nature and character is lost with an autobox. I was also seriously considering an X300 Jaguar, so I have also found out a lot of things about them including from Spectre. They are bulletproof in all conditions, including the winter of Finland: the electrics work fine, mechanically they are great but the only thing that is a worry is rust, but again that may or may not apply in your case.
Also they are two very different types of car, the BMW and the Jag. The BMW will be more of a "driver's car" but on long journeys and sitting in traffic I would expect the Jag to be more relaxing to drive. Also while the 3-liter straight six has 231bhp, it won't be a rocket sled. Neither is the Jag but you don't really expect it to be one in the first place.