Heidi's Hubby,
I currently run an A4 Avant 2ltr Tdi,& tow a Senator Indiana, but used to run Audi Allroads, all 2.5 tdi auto.
The Allroad is based on the A6 Body with modifications for the air suspension.
The 2.5 tdi is a blisteringly brilliant towing engine, whatever model it's in, A4 or A6, bags of torque & ultra reliable, providing the services are carried out at the correct intervals. Early ones were 150bhp, later 180bhp.
Yes, I have to declare an interest here, I work for a group of garages which currently have six Audi dealerships, & have been the service manager at 5 of them at various times.
If you get a quatro model, then fuel efficiency is not good for a car, but is better than the usuall 4X4's, economy on the front wheel drive is better, both solo & towing.
As there is no set levels of trim & options, it all depends on what the original purchaser ordered when the car was new, the fitted options can vary from car to car, but the standard spec for the UK included climate control, alloy wheels and radio cassette.
If you find one you like, let me know & I'll check the service history for you.
They rarely go wrong, & I can't think of anything really to look for, save the usuall, condition, number of owners, mileage & service history, but if they do go wrong, they can be expensive to put right.
By the way, don't take Towsure's listed Kerbside weight, thats for a base, & I mean base model as supplied in Germany! if it's got a service book, look in page 1, at the botton of the sticker (thats the options & build data for that car) is the KW as weighed as it came of the production line. E.G. my current car is listed in Towsure data as having a KW of 1490kg, when actually it is 1618gk, and that makes a hell of a difference when it comes to your outfit matching.
GeorgeB