Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Model S with hitch rack

This site may earn commission on affiliate links.
I’m getting ready to take a 300 mile each way road trip with my P90D. This is a trip I make often, and usually average ~350 watt hours per mile. I’ve never done this trip with a hitch rack and two mountain bikes on it. What should I expect my watt hours per mile to jump to? This goes through rural areas and I’m concerned I may end up stranded.

I did make the trip once with 3 bikes on a roof rack. It was a miserable experience…so much so that I sold the roof rack and have not taken this car on that trip again with bikes. I’ve got no viable alternative this time. If I plan on 450wh/mi should I be safe?
 
My guess is minimal impact to wh/m
Do you notice a drop when adding a passenger or two. Well that’s about what you should see.
I tow a small trailer. Probably 800 lbs. totally flat so no wind hit. I barely notice range difference. But my large trailer, usually loaded and lots of wind resistance. Wh/m can double at times.
 
My guess is minimal impact to wh/m
Do you notice a drop when adding a passenger or two. Well that’s about what you should see.
I tow a small trailer. Probably 800 lbs. totally flat so no wind hit. I barely notice range difference. But my large trailer, usually loaded and lots of wind resistance. Wh/m can double at times.
It’s not the weight I worry about, it’s the increased drag. When I’m buzzing around town with the bikes on (which I do frequently) I can feel it. I just haven’t done a long road trip with them where I’ve really worried about paying attention to consumption.
 
It will be more impactful than you think. We had two mountain bikes on the roof as we blasted through the Rocky Mountains along I70 to Moab and saw roughly 50% the actual range versus what was projected. From what I've read, having them on the rear could be slightly more efficient than roof-mounted but not by a lot. Not having the ability to put all of that air back cleanly behind the car makes for a massive pocket of turbulence behind your car that acts like a parachute in terms of aerodynamics. The higher your speed, the more noticeable this will be and the higher the impact to your range. There's a reason that Tesla makes some of the most aerodynamic vehicles in the industry. It's also evident how important aerodynamics are to highway efficiency when you encounter even a slight breeze.
 
It will be more impactful than you think. We had two mountain bikes on the roof as we blasted through the Rocky Mountains along I70 to Moab and saw roughly 50% the actual range versus what was projected. From what I've read, having them on the rear could be slightly more efficient than roof-mounted but not by a lot. Not having the ability to put all of that air back cleanly behind the car makes for a massive pocket of turbulence behind your car that acts like a parachute in terms of aerodynamics. The higher your speed, the more noticeable this will be and the higher the impact to your range. There's a reason that Tesla makes some of the most aerodynamic vehicles in the industry. It's also evident how important aerodynamics are to highway efficiency when you encounter even a slight breeze.
I know it will be significant. Trying to quantify how significant.
 
I have sea sucker mount and had 2 mountain bikes on top avg about 73mph, 50* outside and was around avg about 430whm over 240 miles so not sure about hitch mount.
I’ve got a Seasucker too, but going with the hitch mount for this trip. I usually average ~350wh/mi. I’ll plan on 475wh/mi. I’m going down for a meeting, tight on time and wanting to make sure I leave plenty of time to charge.
 
Get a RAV4 TRD OFF-ROAD for weekends and dependable fun, and a MSP to do local zoom-zoom.😎


3D148FAF-E107-4EB4-99A2-0940A841FF26.jpeg
A85DC6AE-1AB3-4E9A-BAA0-3D4D2B6D2606.jpeg
 
Get a RAV4 TRD OFF-ROAD for weekends and dependable fun, and a MSP to do local zoom-zoom.😎


View attachment 764635View attachment 764636
I have plenty of cars, but thanks for the suggestion. I’ll post details back here for those interested. I made the trip down yesterday and will make the trip back today. The Model S is my preferred car for this trip (which we make often) but doing it with the bikes adds about 45 minutes of extra charging…maybe more. The trip down here is more downhill than up, so the trip back today will be really telling. More details to come.
 
  • Like
Reactions: krsgio
So, I wanted to try and get a good, real world linger mileage comparison of the impact having a bike rack on the back of the car makes to range. As we all know there are so many things that affect range this is difficult to do.

Well, the last two weekends I made one night trips to the same destination about 280 miles away and back. The weather was more or less the same, left the same time of day each direction, etc… The first weekend, I had my 1UP rack (hitch mount) with two mountain bikes on it. The second weekend, I did not.

I’ve included some photos of the tripometer in the car and also the charging screen in the Tesla app to help visualize how much more energy was used but here’s the details and what I did.

Trip 1 - with bikes in tow: I set the cruise to 75 MPH. You can FEEL the bikes dragging as you drive the car. There were moments when I’d bump it up to 80 for a little bit, but for the most part I was at 75 MPH. I averaged 457 Wh/mi and consumed a total of 283.1 kWh over the 619.9 miles. This trip had a few more miles than the next, because I drove through town to the trailhead. If that had any impact at all, it pulled the average down.

Trip 2 - no bikes: For this trip I set the cruise to 85 MPH (10 MPH faster) and left it there the entire trip. Car felt like it should and does on every other trip. Despite going 10 MPH faster, I averaged 361 Wh/mi and consumed a total of 211.6 kWh over the 585.6 miles.

I wish I had the patience to do the exact same speed on both trips, but I honestly don’t think I’d have enough battery to make it between the two superchargers with the bikes at 85 MPH, and I couldn’t bare going 75 MPH without the bikes - I’m in too big of a hurry.

It was interesting to me though to see that despite a 13% increase in speed the car use <79% as much power. I’d guess at highway speeds you’re looking at a 40% range penalty for hitch mounted bike racks.
 

Attachments

  • 039CA7D9-C4C8-4C0A-865C-2A9674A3E937.jpeg
    039CA7D9-C4C8-4C0A-865C-2A9674A3E937.jpeg
    234.7 KB · Views: 42
  • FEFC6A8C-FF38-4E7A-B888-D81BE783ED36.jpeg
    FEFC6A8C-FF38-4E7A-B888-D81BE783ED36.jpeg
    242.8 KB · Views: 37
  • 46EF60A8-BB24-4406-9050-CCC243FC8E58.png
    46EF60A8-BB24-4406-9050-CCC243FC8E58.png
    210.4 KB · Views: 33
so it seems like hitch is roughly 20-25wh difference more than roof mounted sea sucker
I had a Seasucker and I think the Seasucker was worse. I didn’t do this same exact test, but now I’m tempted to. Problem is I sold the Seasucker.

I should have added it was cold (~20°) for most of the drive and I also had a pretty stiff headwind for part of the drive back on both trips (as is common for that area and time of day).