I know I'm coming in a little late here but I had the same question when I purchased my 1970 31' Sovereign
a few months back...
I also wanted a smaller vehicle as I drive around often to meet clients - I'm a freelance web developer. Out of the total time my car would be driving only 3% it would be pulling an airstream. I also wanted something sporty and fun, as well as practical to fit dog, friends, music equipment, etc etc. I also live in the mountains of WNC.
With the help of Joe at CanAm RV, we narrowed it down to Wagons and a few SUVs. I <3 Wagons!
I ended up purchasing a 2006 BMW 325xi (AWD) for only $16k with only 50,000 miles. I know my deal is not average but still, used BMWs are out there. It took me about 2 months to find the right one.
After reading all of the info on wheels and tires on this thread I may upgrade the rims to 17" (was considering this anyways) and tires for towing purposes and keep the OEM ones as winter drivers.
At first glance you're like "That can't pull an Airstream!" but once you drive it you realize the brakes are superb, the engine is powerful and the Auto with manual option transmission is versatile. It's not setup for towing yet (the AS resto is not done) but I will be driving to CanAm to get the hitch on hopefully sometime next year.
I should mention that my AS will be under the normal weights because I won't have bathroom, water, beds, etc. It will be more of an "office" setup. Probably shaving off at least 1000lbs vs the normal Airstreams people live and camp in.
I wanted a TDI Wagon but Joe said it wasn't recommended for pulling an AS that was as big as mine. The mpgs on my BMW aren't great to be honest. About 20mpg city driving and probably in the higher 20s with highway driving. I'm sure towing won't be much better than 10, probably even less
- it also is supposed to get >91 octane gas, but mid-grade is ok I've heard. (I sill use premium)
It's normally an expensive car to own, but I got it for such a good deal and it meets all of my other needs x10. The space is amazing and it's a pleasure to drive around in the MTNs of NC. BMW is also bringing the Diesel wagon to the US this year for the 2014 models!
BTW - the 3-series BMW wagon is much, much
more fun to drive than the 5-series wagon, but the 5 series felt like it might be a better TV due to it's stability and longer wheelbase. I drove both and picked the one with half the milage.