I mentioned in a previous post that I was likely replacing my Husqvarna riding mower that has the ailing and mostly unserviceable hydrostatic transaxle with my dad's Kubota GR2100, which is far more robust and seems generally better suited for the amount of hills I have in my yard. My dad lives down near Martinsville (about a 4 hour drive from here), and we'd been sort of idly talking about how we might make the handoff.
He has a small trailer that he bought specifically for hauling the aforementioned tractor, and so I had been thinking of maybe borrowing that to save him from having to make the trip. I got the factory towing package when I bought my Model Y, partially because I wanted a receiver hitch for my bike rack but also because it seemed reasonably useful to have another vehicle capable of towing a utility trailer or some similar should the situation call for it. We got as far as checking weights and things and confirming that it was well within the safety margins for the Model Y, but hadn't really planned to make it happen yet. But in the last week, my 100 year old step grandmother was called home, so I found myself in the area on fairly short notice this past Friday. Fortunately my dad had just last week put in an outdoor NEMA 14-30 for me to use for charging, so after the funeral we plugged the car in and set to sorting out the towing situation. Took some digging to find the right combination of receiver hitch/drop, tow ball size, and locking pin, plus the keys to unlock trailer, pins, etc. but we got it all sorted out.
The Model Y's factory hitch has a 7-pin harness including wiring for an add-on trailer brake controller, and a Class III receiver. The Class III is kind of overkill, because the Model Y actually only has a 3500 lb towing capacity, with a 350 lb max tongue weight, which is technically within the limits of a Class II hitch. This does assume 3 passengers, so I suspect you could probably push it beyond that and not exceed the GVWR/GAWR, but I probably wouldn't go north of 4000 lbs even with a trailer with brakes, mostly because I'd be concerned about the rear end squat. As it was, because this doesn't ride particularly high (it's really more of a tall wagon than something with any pretention of being an SUV), I had to use a hitch with basically zero drop, and I was careful to get the meat of the load's weight over the trailer axle to avoid too much on the tongue.
The trailer in question weighs about 1000 lbs, and the tractor is listed at 940, though I suspect that's dry weight, so it's probably around 1000 too, meaning we're at a nice even ton, plus just me in the car, meaning a total rig weight of around 6800 lbs. This trailer doesn't have brakes, but that really wasn't a big deal, because between the regenerative braking and the fact that the Model Y has pretty strong friction brakes, I was never concerned about the stopping ability for the whole rig. I'd want at least some surge brakes if I were hauling another 1000 lbs though.
Prepping for towing
Accessing the hitch involves prying off a plastic cover on the rear fascia with a flat blade screwdriver. My Jeep had a cover, and it had thumb screws. This has plastic friction clips, and let's just say I suspect they probably only survive one or two removals no matter how careful you are. It's not a great design. Once you have the cover off, hopefully with all of the clips intact, you discover that the amount that the hitch is recessed, combined with the relatively small opening means that you're sort of fumbling around to get the hitch pin in place, and probably some longer ones might not fit at all, especially depending on the orientation of the lock. Additionally, the chain ears are way up inside the recess. Smaller hands probably make that easier to manage. Again, this is a case where the people who designed this probably didn't do a lot of towing. The rear camera does make it super simple to line up the ball and tongue. That's not unique to Tesla, but it is really nice to be able to turn on the camera when you're underway to check that part of the trailer. My trailer was fairly short, and about the same width as the car, so the regular mirrors were adequate once I adjusted them a bit, but a longer or wider rig would require towing mirrors, which would add drag and affect range.
Plugging in the trailer harness activates Tow mode, which according to Tesla disables Autopilot, increases the following distance for the adaptive cruise control, and supposedly uses some different logic on the stability control to help manage trailer sway, something I thankfully did not have to test. I understand why they'd disable auto lane change, but I've grown very accustomed to using Autopilot's lane keeping, especially on long trips, and would have liked to be able to use that, especially since there are some times that you really do need to be able to look at the screen for a minute, and having something handle keeping you literally between the ditches is a great help.
Actual Towing
Tow mode has a major thing missing, in that it doesn't adapt the car's baseline range estimates or trip planning algorithm at all. I get that every trailer is different, and the weight, aerodynamics, etc. all affect range differently, but at the very least, they could characterize a generic impact on range from towing and use that. This is an area where it's better to be a little conservative and end up with more range than you thought than dealing with constant range anxiety or worse, actually being stranded because you didn't stay ahead of the aggressive burn rate. Even if there was some way to manually tell the car to assume a certain percentage drop in range when planning the trip and determining needed charging stops, that'd be an improvement. But the car's default range displays were still claiming what is effectively ideal (aka only achievable on the EPA test cycle) range, and calculating charge stops according to Tesla's standard usage projections (which are more real-world accurate than EPA). What you end up having to do is put in your destination, drive for 30+ miles, which is long enough for the energy usage screen to get an average usage with you towing such that it can project your range based on the past 30 miles of historical burn rate, and then you have to compare that with how far the Nav system says you're supposed to be going. When it almost definitely is longer than your available range, you have to find a Supercharger on your route and add it manually. To make matters worse, because you have basically no sense for how much more range you're going to burn, you have to keep checking this periodically to make sure that you still have enough range to make it to the charger you chose, and then once you're at the charger, you have no guidance on how long to charge. I erred on the side of caution and charged back up to almost full, which meant that instead of the normal 15-20 minute stop to gain back 100-150 miles of range, I was looking at closer to 50 minutes, because the charge rate tapers off dramatically as the battery gets above about 80% charge.
Charging while towing a trailer, in addition to being something you'll be doing repeatedly and often, is also a bit challenging, and again seems to be mostly an afterthought rather than something that Tesla tested or consulted with people experienced with towing to work through the logistics. Tesla charge ports are near the driver's side taillight, and because of the large cables involved in carrying 250kW @ hundreds of volts DC, Tesla makes them short and expects you to back into the space to charge. They have started putting at least one pull-in space in, but that's not universal, and it's not always that helpful, i.e. it's not longer than an average space, and it's not pull through, it's just nose-in parking. Only one of the two Supercharger stations I used even had one, and in order to use it, I still had to pull in with my nose well into the adjacent space (blocking a second charger from being used), and my trailer was hanging out into the parking lot, only narrowly avoiding blocking the air compressor, to the annoyance of at least two Sheetz patrons while I was there. Someone pulled into the space in front of me and then left the parking lot, so I couldn't ask them to move, and so in order to get out, I had to back up with the trailer already halfway to jack-knifed. I managed to do it, but it took a good 10 minutes of back and forth. The second charging station had no good options, so I had to drop the trailer elsewhere in the parking lot, charge, then go retrieve it and reattach.
Driving dynamics are fine, and it's a solid tow rig from that perspective. It was stable and predictable as far as handling went. Electric cars have stupid amounts of torque, and Teslas are overpowered, so the car barely noticed that the trailer was back there in terms of moving itself along at typical speed. It just used more juice. The trip is mostly highway, the majority at 60mph posted limit, with a few sections of 55, 65, and one 70, along with drops to 45 at traffic lights. I ran a bit above whatever the limit was, and even on the hills, there was no issue maintaining speed. One thing I did notice is that I didn't get as much regen braking as I would have expected going down hills, because the trailer's weight wasn't enough to overcome the increased drag. The only time I got any significant regen was when I was slowing down, rather than just maintaining speed on a downhill. The adaptive cruise control was surprisingly quick to adapt to the extra weight in terms of slowing the car down when needed.
As I noted, this comes with a harness for an external brake controller, but I'm somewhat curious if you'd get enough control to really take advantage of the dual braking. Specifically - Teslas do regen braking as soon as you take your foot off of the accelerator. The brake pedal actuates the friction brakes directly, without any attempt to try to simulate braking with regen for the first bit of pedal travel before actually applying the friction brakes like many other hybrids and electrics do. Because the regen braking is so aggressive, the brake lights come on as soon as you lift off of the pedal. Assuming that the brake controller keys off of the brake pedal being actuated, the trailer brakes wouldn't be activated unless you need more than regen alone can provide, but you'd have to tweak the sensitivity carefully to ensure that you still are getting as much regen as possible. Seems to me that there's an opportunity to have integrated the trailer brake controller to make the entire system smarter and more efficient, but at this point I don't think Tesla is that invested in making this a full-time tow rig. I'll be curious to see how they do it differently on the Cybertruck, since that has to compete with actual trucks, most of whose manufacturers have spent a lot of time sweating details to make towing easier.
By the Numbers
Here are the details of the trip, in terms of miles traveled, power used, etc.
The trip down was effectively a control, because I didn't have the trailer. That leg, plus a bit of other driving around, was 269.5 miles, used 75 kWh, at an efficiency of 277 Wh/mi. Using standard conversion, this works out to 132 MPGe. The actual trip MPGe was probably a bit higher than that, because that figure included probably 40 minutes of me sitting with the AC on before the funeral, and a couple of "check out how fast this thing accelerates" starts for my dad. I used a combination of home charging and supercharging, so the fuel cost would be somewhere between $9 and $25. (I'm still using the last of my free supercharging, so I have to estimate based on what the going rate is rather than telling you what I actually paid.)
The return trip was more direct. I started at 100% charge. The Model Y has a 75 kWh battery, and I charged to about 95% at both stops, though I didn't actually need that long of a charge at the second stop. I traveled 242.1 miles, which used 141 kWh, at an efficiency of 583 Wh/Mi, or 62.9 MPGe. That would cost between $15.50 and $48 depending on how much was Supercharging.
That was comprised of the following legs:
- Ridgeway to Lynchburg: 82.7 mi, 51 kWh, 613 Wh/mi, 59.8 MPGe
- Arrived at 24% charge
- Indicated range was 70mi, estimated range (based on last 30 miles' average) was 29.
- Lynchburg to Madison: 96.1 mi, 57 kWh, 591 Wh/mi, 62 MPGe
- Arrived at 17% charge
- Indicated range was 84 mi, estimated range was 27.
- Madison to Manassas: 63 mi, 34 kWh, 532 Wh/mi, 68.9 MPGe
So the short answer is that you lose about 50% of your rated range, which is probably pretty equivalent to the haircut a petrol-powered vehicle takes to its range while towing, but on account of the reduced capacity, it is both impressive in terms of its efficiency, but also barely adequate in terms of being able to comfortably make it between Superchargers without careful planning. For me, it's nice to know I can do it if I need to, but clearly the sweet spot is short trips where the 100-ish mile max range isn't much of a concern.
