I was a bit thrown off by the review thinking it was Euro, but its Canadian... Where do they get off talking METRIC to decent folks...
I own a 2014 E250BT bluetec with the 2.1L I4. Its a wonderful little engine. I replaced my 2006 E320 CDI with the inline 6 diesel and hardly notice the difference except for the even better mileage. I routinely get 40 plus around town and occasionally 50 on the highway. There is no real good hitch option for the e-class (yes there are some not so good choices and in europe there is a little drop down noodle option), and the suspension just isn't rated for towing something with 750 lbs tongue weight like the trailer in the article.
I did look into the E-Class wagon (E350), which does have a beefed up suspension and is set-up for towing, but alas there are no plans for a E250 Bluetec version here in the US.
Would I tow a 27 footer with a GLK? NO. And my 23 foot Safari would be in my opinion marginal. I test drove one before I bought the E-Class and it simply doesn't compare handling wise. The seats are typical small Mercedes seats (too hard), and the drive was way too busy for my tastes.
Not really in the market for a new tow vehicle, but in a couple of years, maybe. I have a 2008 Escalade EXT that is still performing very well, and although the mileage is poor by comparison, the ride and handling are very comfortable and very secure.
If I look at anything, it would be the forthcoming Volvo XC90 hybrid.