Mid-life crisis tow car?

I currently have a supremely capable 2005 Kia Sorrento XSE which is as slow and thirsty solo as when towing. It's a bit of a barge even with 18" wheels and frankly I need a little more spice in my life from my car! 

It needs to tow a 1499kg Bailey Peg II and put a smile on my face when I drive solo.  I have been looking at options like a Mercedes E320CDI Estate, VW Passat 3.2 FSI 4 wheel drive, BMW 535D Touring. Budget 10-12k & trade-in. Would any of these fit the bill or other suggestions to keep me happy in my mid 40s?