Generally towing for NON TOWING RATED vehicle is limited to 1200lb. This is a rule of thumb number. If you drive on flat surface, vehicles can tow a lot more without problems, but if you have hills or mountains, vehicle brakes, engine and transmission cooling system is not designed to deal with extra heat generated by trailer weight, that's why 1200Lb was considered safe limit.
A company named CURT Manufacturing LLC sells US made trailer hitches for the Encore. Towing capacity up to 2,000 lbs.
But DRAW TITE has one that is certified for 3,500 lbs towing weight. This offers a towing capacity similar to those we have here in Europe, i.e slighltly superior to what Opel / Vauxhall has authorized for the car. We can order the Mokka X with a factory installed Hitch ( manufactured by Brink in the EU). I don't know why Buick does not offer that possibility for the Encore, it does not make sense.
No drilling or welding required. It is a simple bolt-on job, plus wiring kit and you're done.
You should / could send an email to Draw Tite in case you are in doubt. They will certainly provide all the informations you need.
OPEL/Vauxhall in Europe are offered with manual transmissions which does not need cooling , ENCORE does not have that option in US, its only Automatic. US version has different radiator with transmission cooler in it. Automatic transmission can and will overheat if vehicle is overloaded and cooler is not sized for that. So it not same vehicle in term of powertrains. As for hitch rating 3500lb, its only metal rating for hitch itself. You could I suppose get a 10 000 lb hitch made up for Encore, does not mean your vehicle can tow that much.
Opel/Vauxhall Mokka X are offered with Automatic transmission as well, so I believe that your worries are not that justified.
BTW, the 153 HP version of the Mokka X is or rather was only available in combination with AWD and Automatic. (It has been discontinued just last week, simply because PSA did not want to pay to update it and keep it conform to new EU emission norms coming next september. They hit Direct Injection engines hard. The 138 HP version remains available, either as FWD with Manual or Automatic or as AWD but only with 6 Speed Manual.the combination of AWD and Automatic was exclusive to the Direct Injection engine, this is what made it the favorite version in Switzerland were the extra torque is appreciated, for obvious reasons.)
The trailing capacity mentioned in my previous post is valid for both engines with Automatic as well. A hitch rated at 3,500 lbs makes sense for a car that can pull 3,306.9 lbs or even 2,645.5 lbs. I certainly would not recommend to tow a trailer that weights about as much as the car though! One has to be reasonable and keep a comfortable safety margin.
The reason why the Buick is supposed not to tow while the Opel/Vauxhall actually does, will always remain a mystery. (And if I asked Opel/Vauxhall why we do not have the folding front passenger seat that the Buick encore offers, I would not get an answer either.)
As far as I am concerned, I still have to be patient, as my car is still one month away on a Ro/Ro ship. And it is an AWD with Automatic AND factory installed trailer hitch!