Aerodynamic efficiency and range: the effect of mounting a receiver hitch on a model 3?

[PhysicsGuy]

I recently had a stealth brand receiver hitch/tow package installed on my 2018 LR AWD model 3. It would be convenient some of the time to just leave the receiver hitch on the car, as shown in the picture here. Does anyone have a guesstimate as to how that might effect aerodynamics, range and efficiency when driving on a more or less level highway at 75 mph? Do you think I will notice a difference: maybe 2, 5 or 10% reduction of range?

Mostly my long distance drives are on highway 101 in California between around San Jose and the north Los Angeles area.

 

[beastmode13]

I’m doing the same installation this weekend. Subscribed.

 

[jjrandorin]

I recently had a stealth brand receiver hitch/tow package installed on my 2018 LR AWD model 3. It would be convenient some of the time to just leave the receiver hitch on the car, as shown in the picture here. Does anyone have a guesstimate as to how that might effect aerodynamics, range and efficiency when driving on a more or less level highway at 75 mph? Do you think I will notice a difference: maybe 2, 5 or 10% reduction of range?

Mostly my long distance drives are on highway 101 in California between around San Jose and the View attachment 660881north Los Angeles area.

Lol... since your screen name is "physicsguy" I thought the thread would be about you telling us the results of your looking into this, not asking about it

Let us know what you end up finding out.

 

[Zoomit]

Do you think I will notice a difference: maybe 2, 5 or 10% reduction of range?

Absolutely not. The difference in range will be well under 1.0% and at least an order of magnitude lower than would be discernible via on the road efficiency testing. There are just too many variables that would need to be tightly controlled.

To be even attempt to measure it, you'd need to measure the apparent wind velocity to much better than +/-0.5 mph, as well as direction, which is not realistically possible given that the winds are constantly changing in an uncontrolled environment. Then you'd need to know how the car's Cd varies by wind yaw angle. The list goes on...

 

[MasterC17]

Can't imagine the hitch alone would affect efficiency to a measurable degree. Maybe up to 1%?

 

[eigenv1]

I recently had a stealth brand receiver hitch/tow package installed on my 2018 LR AWD model 3. It would be convenient some of the time to just leave the receiver hitch on the car, as shown in the picture here. Does anyone have a guesstimate as to how that might effect aerodynamics, range and efficiency when driving on a more or less level highway at 75 mph? Do you think I will notice a difference: maybe 2, 5 or 10% reduction of range?

Mostly my long distance drives are on highway 101 in California between around San Jose and the View attachment 660881north Los Angeles area.

This might be a minor issue only at high speeds. How laminar is the flow at the rear bottom of the car? Try a CFD program to get an idea or attach some lightweight streamers around that area and have a friend drive along side of you to see if the streamers are flagging. Another alternative is to call UP, since they have done such testing. If the flow near the hitch area is pretty laminar, you could mitigate the turbulence at the leading edge of the hitch by 3D printing a flow splitter with a pointy end forward to attach on the front of the blocky part of the hitch. Payback time: 100 years.

 

[PismoPat]

This might be a minor issue only at high speeds. How laminar is the flow at the rear bottom of the car? Try a CFD program to get an idea or attach some lightweight streamers around that area and have a friend drive along side of you to see if the streamers are flagging. Another alternative is to call UP, since they have done such testing. If the flow near the hitch area is pretty laminar, you could mitigate the turbulence at the leading edge of the hitch by 3D printing a flow splitter with a pointy end forward to attach on the front of the blocky part of the hitch. Payback time: 100 years.

I can picture a pointy cover for the receiver that locks into the hitch the way the trailer does, but points forward with a bike rack type of lock. We could probably scale the manufacturing and get the break even down to about 87 years.

 

[PismoPat]

Tesla probably knows the answer.

 

[Watts_Up]

Just top of my head, but there are some Youtube videos regarding
the effect of the Model 3 Roof Rack, and the range effect was negligible or not noticeable.

So I don't think you could even measure some difference.
The only worry would be the risk of hitting the ground when passing over some big dip.

Since the Model 3 is very low, some people recommend to make a hole in the rear bumper
so the receiver will be about 6 inch higher than the one you have.

 

[Young Phenom]

Negligible

 

[jackmott]

3d print a tear drop trailing edge to stick in the end of it