Tow vehicle question, BMW X5? Options

[Part Pricer]

I'm looking at possibly picking up a BMW X5 as a daily driver and tow vehicle. Because of the tax laws, it makes a lot of sense to get something with a GVWR of 6,000 lbs or over. I'm also somewhat concerned with gas mileage. For this class of vehicle, the BMW X5 and the VW Touareq get the best mileage. There both nice vehicles. But, I would probably go with the BMW if it can meet my towing requirements.

The X5 with the 3.0 has a listed towing capacity of 6,000 lbs. I would be towing a Trailex open trailer that weighs just under 1,000 lbs loaded with a Boxster that comes in around 3,000 lbs. So, according to my math, I'd be pulling around about 4,000 lbs.

Am I missing anything here? Do you think it would fit my needs? Anyone else using an X5?

Thanks

[ChrisFoley]

IMO a 3.0 liter engine will not handle the task of towing 4000 pounds unless you're just going down the street and back.
What is the curb weight of the potential tow vehicle? If it is less than the weight of the fully loaded trailer it's not a good idea to use it for towing, from a safety standpoint.
You want to have one vehicle to handle two very different tasks: 1) daily driver 2) car trailer tow vehicle. No automobile does both of these well, unless your commute is very short or the car is very small (radio controlled for instance).
I would encourage you to find someone already using such a vehicle as you want to buy for the same purpose and get them to show you how well it works. Then decide if you still want to go that route.
I sometimes tow my race car trailer (<3000lbs) behind my 2002 Dakota (big 6 cyl), which is also my daily driver for an 8 mile commute. It works fine but I wouldn't want to use anything smaller for the towing job. I get about 14mpg commuting.