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Comment by roflchoppa | Hacker News Reader

Ohhh there was this YouTube video (from Motortend?) showing a model X in tow that had a drastic reduction in range when towing a trailer.

Now compare that to the LandCruiser that we haul race cars with… the LC always gets 14 mpg, we have filled it with 6 adults going to Tahoe, same MPG. Haul a 2700lbs sports car. Doesn’t change at all.

Honestly an EV would be nice for hauling stuff to the track, hopefully with the race car, and equipment it can make it to Willows on a single charge, at least the track has RV hookup points, can charge while you race.

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> Now compare that to the LandCruiser that we haul race cars with… the LC always gets 14 mpg, we have filled it with 6 adults going to Tahoe, same MPG. Haul a 2700lbs sports car. Doesn’t change at all.

This is physically impossible unless the LandCruiser is just throwing energy away when empty.

What's more likely is that this estimate is not very precise.

Considering the LandCruiser is pretty much a box with maximal air resistance, it might actually get more aerodynamic by adding the trailer to it :p. So the difference while trailing would be much smaller than adding a trailer to an aerodynamic car. Energy consumption when trailing with constant speed is mostly about aerodynamics.

It is believable. Towing is more about wind resistance than about mass. A car on a trailer is probably sitting mostly in the slipstream of the LC (they are not very aerodynamically shaped) and so not contributing much to the total wind load. Also engines to a point become more efficient under load. All told, there probably isn't a noticeable difference.

Of course we are talking about towing a light sports car here. Tow a different type off trailer, or a very heavy load and the losses will start to catch up.

In addition to wind drag, the additional weight contributes to the acceleration work required by the engine. This acceleration is occurring during cruise speeds as well as starting from rest (you can tell because your car engine is louder during cruise speeds than it is while the car is idling from rest.) Anything towed or carried contributes to the weight of the car which means the car is accelerating more weight. The curve isn’t perfectly linear with additional weight, as you noted, but the reduced MPG is measurable with a number of passengers in the car, let alone a towed car. A reduction of only 10-25% mileage might not be noticeable to a less observant driver but that isn’t to say it’s effectively the same.

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