In that case i would suggest a BMW 530D.... trouble is with the 3 Series is everyone who drives one is a w*nker!
5 Series have less of an image problem, and in 3.0D form, i think are very nice!
Would fit the bill as they hold their value very well....
or get the Jag, and use a Motorbike to commute 
530d is nice, but I can't get over the whole diesel thing, I think unless you're doing mega miles they're not really worth it (especially with diesel being more expensive to buy now, which cuts into the savings). Personally I'd be more inclined towards the 530i, you'll get a much nicer example for the same money, probably lower miles too as the diesels tend to be high mileage for obvious reasons. It handles better than the diesel, and the inline-6 engine is a peach, sounds very nice for a 6-pot IMO, much nicer than the GM V6. Rack and pinion steering on these too so the steering feedback is good.
IIRC the later E39 530i are around 235 BHP so they're reasonably quick, particularly if you get the manual version, which aren't too hard to find as a lot of the enthusiastic drivers go for the 530i sport. Not sure why but there seem to be more 530i in sport trim than 540i, maybe because the latter has a recirc ball steering box, or it might just be down to price.