TFL's teardrop towing test was flawed in part because they did not measure the mileage for the non-towing vehicle over the same course. The other videos I've seen from them use one vehicle as a chaser while the other tows - after the first out-and-back they compute the actual MPG for both the towing vehicle and the chase vehicle, then they switch the trailer to the other vehicle and do it again. When they do this they have both a towing MPG and a non-towing MPG measured over the same course in roughly the same conditions.
In the teardrop video, they didn't use a chase vehicle, they just measured MPG/range while towing. So we don't have an exact denominator to use for a MPG/range calculation. BUT we can get a rough estimate of the range reduction based on what they said in the video and based on their previous test with this same Tacoma.
In the video they stated the range of the Rivian was 280 miles, but I don't think they measured that - in other videos they have said 314 - 10% for the 20" tires/off-road trim, which comes to 280. This is probably not far off, as we have seen many other tests which confirm the EPA rating and we have other data that validates the range loss for the AT tires and the added weight of the off-road package. If anything, 280 is probably a little high. However they really should have obtained a real number for the course they were towing on.
Likewise, in a previous video (the Tundra vs F150 towing test) they measured that exact Tundra as 24 mpg, not towing. I think that's high compared to the EPA rating, but that's what they measured. Again, they really should have done the measurement on the same course they used for the towing.
If you take these initial numbers, and use the measurements from the towing video (Rivian tows 168 miles on 100% charge, Tacoma tows 153 miles on 10.348 gallons), then what you get is that Rivian lost 40% in range and the Tacoma lost 38.5% in range. As expected, the range reduction is really all about the trailer and how much extra energy it takes to pull that trailer, which doesn't depend on the tow vehicle. And if you know the range reduction for your trailer you'll get roughly the same range reduction with the Rivian.
