2016 Tesla Model X: Tow Test Reboot With a Happier Camper Trailer
by Dan Edmunds, Director of Vehicle Testing
Unlike any other electric vehicles on the market, the 2016 Tesla Model X is able to tow a trailer. The maximum Model X tow rating is 5,000 pounds, but any Model X fitted with the optional 22-inch wheels, such as ours, is limited to 3,500 pounds. The bigger wheels come with ultra low-profile tires that aren't able to bear as much weight because it's the air volume inside a tire that carries the weight.
But we know from experience that these numbers don't tell the whole story. Towing on electric power is complicated by the realities of range and recharging, two critical factors that are ignored by the official tow-rating process. Last summer these issues made for such an unpleasant first experience that, after it was all over, I wrote, "I'm not sure I ever want to do it again."
For various practical reasons the trailer we'd borrowed from Off the Grid Rentals was a specialized adventure trailer intended for off-road towing behind a Jeep or Land Rover. We appreciated the trailer in its own right, but its combination of huge off-road tires, massive jutting fenders and exposed external equipment made us wonder if some unseen excess of aerodynamic drag and rolling resistance had been especially hard on the Tesla. It has been a nagging question.
So we're doing it again. But this time we're using an enclosed fiberglass camping trailer from Happier Camper. Just looking at it, the HC1 model is a much more obvious and compatible partner to the Model X. But will it make a difference? Will the Model X do better with a more conventional trailer in tow?
The Happier Camper
Happier Camper's HC1 is a compact single-axle hatchback trailer that's reconfigurable by the user to function as a camper, an enclosed bicycle/motorcycle hauler or both at once. Its empty weight ranges between 1,300 and 1,500 pounds, depending on equipment, and its maximum loaded weight is 3,500 pounds. And unlike in the high-clearance adventure trailer, the HC1's tongue height matches up exactly with a standard ball mount plugged into the Model X's receiver.
It's also narrow enough that extended tow mirrors are neither legally required nor remotely necessary to see down its flanks. It also has front and rear picture windows that are strategically located so we could use the Tesla's center mirror to look through the HC1 and clearly see traffic directly behind. Unless you've towed before, it's hard to appreciate how truly unique and reassuring this is. So far so good.
Less of a Drag? Do I Hear More?
The HC1 is decidedly more cube-shaped than the teardrop-style adventure trailer we pulled before, and the base size of the HC1 is 17 inches taller and 22 inches wider. It's only 3 inches wider at the base, though, because it has internal fenders, not the protruding external fenders of the teardrop. It's not a large trailer in an overall sense but, compared to what our Tesla pulled last time, the HC1 nevertheless punches a bigger hole in the air because it does have more frontal area.
On the plus side, it has stylishly rounded corners, subtly raked contours, and small, 13-inch trailer tires that are tucked neatly within the shape. There are very few protuberances, and it generally looks far smoother and friendlier to the passing air than the adventure trailer ever could. In aerodynamic parlance the HC1 appears to have a much lower coefficient of drag (Cd) than the adventure trailer.
At a given speed, the drag force generated by an object is directly related to its drag area, which in this case is the trailer's frontal area multiplied by its Cd. Our cute little trailer has more of one and less of the other, but it was impossible to know which factor would have more influence because a trailer rides in the slipstream of the vehicle that's pulling it, and that makes the math go all wonky. We didn't know which way it would go.
No More Weight Than Necessary
That helping of doubt was compounded by another. Our planned route included numerous grades between our sea-level starting point and our target lakeside campground some 500 miles away on the shore of a reservoir perched at 5,614 feet. The highest Supercharger on our route stood at 7,880 feet, and we climbed over higher summits than that along the way.
On our last trip, we experienced almost double the electricity consumption when towing, which is another way of saying that range was cut nearly in half. The distance between adjacent Supercharger stops had felt uncomfortably close to the limit.
We had no desire to do that again, so we decided not to push our luck when it came to weight. We loaded the trailer with no more than we'd usually bring on a trip like this: a mountain bike and some basic camping gear. That made our Happier Camper weigh right around 1,500 pounds — the same approximate loaded weight as the trailer we pulled last year.
The Journey Is the Destination
The outbound 500-mile leg of our 1,000-mile round-trip journey would normally be manageable in a single day with a gasoline-powered tow rig and a strong bladder. But we planned for two days out and two days back because the pace of last year's Tesla tow trip to Flagstaff, Arizona, had been slowed by long and frequent recharging stops.
There's no way around this, so it's best to adopt a mindset along the lines of "The journey is the destination." Short hops, frequent stops is the name of the Tesla towing game, and that's just fine when the point of the trip is camping and recreation. Might as well plan for it.
That's why we changed our route to follow a line of Superchargers sprinkled along U.S. Highway 395, a gorgeous drive up the eastern flank of the Sierra Nevada mountains. Camping options are numerous, too. Our previous excursion to Flagstaff followed a largely desert route that passed by the California cities of Desert Hot Springs, Indio and Blythe as well as Quartzsite, Arizona, and the northern Phoenix suburbs before finally ascending into the mountains in the final 100 miles. Midpoint camping options were limited, not to mention ungodly hot and lacking in scenery.
A Tesla dashboard can bombard you with more charts, graphs and tabular information than a tax accountant could make sense of, but there's one particular figure that tells you the exact rate at which your Tesla sucked electricity out of its battery from one charge stop to the next. It's called average energy consumption, and it is displayed in watt-hours per mile.
There's a faint guideline on the energy consumption graph of every Tesla. It represents how many watt-hours per mile you must average to achieve the rated range. Our Model X P90D is rated at 250 miles, and to match that a driver must average 330 watt-hours per mile.
Last summer our Model X averaged just 612 watt-hours per mile towing the adventure trailer to Flagstaff. I recalculated that in terms of range and came up with just 135 miles. Our average recharge time of 1 hour and 34 minutes was pretty dreadful, too.
Can our Model X do better towing a cute but somewhat larger fiberglass-bodied Happier Camper trailer despite a more mountainous route? Check back soon to find out.