A single piece of purely anecdotal evidence, so take it as you will: I just towed a fully loaded 4'x8' U-Haul trailer from through Canada and down to Los Angeles (roughly 3,000 miles) with my 2013 C-Max Hybrid. We took the mountains pretty slow and tried to be as cautious as we could at avoiding rough terrain. Not sure what the longer term effects on the suspension/transmission will be but the car performed well and came out unscathed as best I can tell. Hard to fully guess the loaded weight of the trailer, but I would put it somewhere between 1,200-1,400 lbs. The car claimed to average just over 22 mpg over the entire trip (though I didn't actually track that manually)