Towing is a special challenge for all tow vehicles. Total weight is greatly increased, as is air resistance. Going over bumps can produce “porpoising” in the linked vehicles. Improperly loaded trailers can swing around or jackknife. Braking can be tricky on our steep mountain passes, especially if the tow vehicle’s brakes are not equipped to handle the extra weight or the towed vehicle lacks properly calibrated and linked brakes.
The importance of air resistance was brought home to me by a friend’s account of his trip into a strong headwind on I-25. He was towing a modest 16’ RPod travel trailer with his Subaru. Because air resistance scales at the cube of the airspeed (a car going 70 mph into a 50-mph headwind has resistance proportional to the cube of the 120 mph windspeed, or 216 times the resistance of the same wind conditions when traveling downwind and 5 times the resistance of a vehicle traveling 70 mph in still air), the gasoline-powered Subaru’s fuel economy dropped down to 3 mpg! He ran out of gas; called AAA, which brought 2 gallons of gas for him. Unfortunately, he was 8 miles from the next exit and this “bailout” took him only 6 of those. Wind direction really matters when towing.
Electric tow vehicles are no different from gasoline-powered Subarus except that fast charging EV fuel stations are often more widely spaced than gas stations (most of us will live to see that inequality reversed!).
We recently towed a modest 16’ travel trailer (see photo above) 1400 miles across Arizona to test the ability of a 410-mile (maxPack) Rivian R1T pickup to manage with the fast-charging stations now available (at the time we did not have the NACS adaptor now being distributed to Rivians and Fords to enable them to use Tesla Superchargers).
One good feature of the R1T is that it recognizes each trailer that it pulls by its electrical signature and computes the trailer’s effect on fuel economy (https://ev4corners.org/the-rivian-pickup-truck-review/), while correcting for temperature, topography, and land speed (but not airspeed or driver aggressiveness). Our trailer weighed about 2500 pounds loaded. The correction for the extra weight and air resistance worked out to a 29% range penalty in our case. In other words, maximum range 410 miles without trailer, 291 miles under average conditions with this particular trailer. The penalty would be larger for a trailer that did not “pop-down” when being towed. Other tow vehicles have different towing penalties for the same trailer; for example, Motor Trend estimated that a 25% towing penalty for a particularly streamlined 3170-pound trailer (www.motortrend.com/reviews/2024-tesla-cybertruck-vs-rivian-r1t-vs-ford-f-150-lightning-comparison-test-review/) with the Rivian resulted in a 33% penalty for towing the same trailer by either the Tesla Cybertruck or the Ford Lightning. A small trial towing our pop-up trailer with a gas-powered RAV4 yielded a tow penalty of around 52%; thus, EV trucks don’t seem too bad compared to ICE cars.
The weather was particularly unhelpful on the day we had planned to head south, with 50 mph headwinds forecast for the first 200 miles of our journey. The winds were to die down the following day, but considerable snow was forecast for the intervening night at our home. We did not want to be towing in snow, nor drag the trailer through the resultant mire of muddy roads that lead from our home. Instead, we opted to tow the first 50 miles ahead of the snowstorm, landing us at a commercial campground in Farmington, New Mexico, where we were able to spend the night and dewinterize our travel trailer (purge the antifreeze from the plumbing and replace it with clean water).
The next day the winds were mostly mild, but we did watch our range forecast to be remaining at the Gallup, NM, fast-charger dwindle steadily as we pushed through the winds that were ahead and across us. The road from Shiprock to Gallup is notoriously potholed, and our anxieties about porpoising were ameliorated by the superb stabilization in the Rivian. Motor Trend calls the Rivian “imperturbable” when towing on rough roads, in contrast to the Tesla and Ford EV pickups, which they found to kick disturbingly.
The instructions on the Electrify American fast-charging station in Gallup were exactly the opposite of what was required, so we spent more time trying work-arounds than we did actually charging. Also, this particularly charging station is in a very busy Walmart parking lot, so we had to unhitch the trailer before approaching (and rehitch after leaving) the charging station. Fortunately, we had only a 1.5 h drive to the Rivian charging station in Holbrook, AZ, which was not only cheaper and unused, but also featured a drive-through charger for use with attached trailers (pic below).
The climb up onto Arizona’s Mogollon Rim was uneventful and left us with just enough charge to make it all the way to our accommodations in Phoenix. Just in case, we topped off for a few minutes at the Electrify America fast charger in Payson (again having to call EA for assistance with hooking up).
Phoenix is crawling with Teslas (we counted about 3 visible when stopped at every major intersection), but Rivians were very scarce. Before leaving town, we topped off at a Rivian charger in a parking garage at a nearby shopping mall. The six Rivian chargers were not in use, so we were able to hog some slots and not have to unhitch for the 25 min duration of our fast charge.
We then traveled to the Tucson Mountains, where we spent a week biking, hiking, and camping at a park. The campground’s electrical infrastructure was able only to support only level 1 charging, but that was enough to offset our daily trips and nearly fill the Rivian before our return trip.
We stopped again in Phoenix on the way back. The only real difference was that four Rivians were at the Rivian charger facility on this visit; fortunately, we had unhitched the trailer at our accommodation. We again got a solid fill up at the Rivian charger in Holbrook.
The Electrify America charger in Gallup was again a hassle, as we had decided earlier in the trip to capitulate and become a member of Electrify America (EA) to ease the pain of charging through their network. Only, it turned out that “joining” at their recommended level offered us zero discount ($0.56/kwh) and only the “privilege” to receive regular advertisements for EA through our email address. Membership, however, also changed the procedure for starting a charge, to another new sequence that directly contradicted the instructions on the charger. Out of irritation, we cut short our charge and drove away.
The Rivian navigation program however had other ideas. It kept directing us to turn around and go back to Gallup. It refused our efforts to charge elsewhere instead, until we eventually found a way to lower the default number of required miles remaining at our destination, which calmed it down. We also gained from a following wind. And just for the knowledge gained, we made a short stop in Farmington, NM to top it up. The price was the highest we encountered ($0.60/kwh), but our overall fuel cost for the trip amounted to about half of what we would have paid for gas in a comparable ICE (Ford F-150) tow vehicle.
Although the ease of filling up at fast chargers is still a work in progress, the 40+ fast-charge providers nationwide are making steady progress at seamless billing and a single standard for connectors. Most chargers than we encountered were capable of at least 250 kw, which allowed the necessary charging to occur in 10-40 minutes. We are clawing our way up the EV-charging learning curve as well. Two major conclusions stand out: 1). We never waitedmore time for a fill-up than was an enjoyable break and we never had to wait for a charger to free up. That might change as electric driving becomes more popular, but the adoption of a single charging standard and the Infrastructure bill’s new charger build-up should improve prospects dramatically. 2) Despite towing through the sparsely equipped northern reaches of New Mexico and Arizona, we never struggled to reach an open charger.
