Range with Tonneau open or close

[SeaGeo]

Has anyone asked Rivian if they can share any data on the impact of the tonneau position on range? I'm inclined to leave mine open unless I have a reason to close it as a way to protect it from the elements.

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[the long way downunder]

Has anyone asked Rivian if they can share any data on the impact of the tonneau position on range? I'm inclined to leave mine open unless I have a reason to close it as a way to protect it from the elements.

Closed will be less drag unless Rivian has an effective spoiler on the roofline (it doesn't look like anything more than a design flourish.)
Years ago an aero test (wind tunnel) of the pickup body showed that with the bed open, there is less drag if the tailgate is closed (not open.) It was a long held but mistaken belief that dropping the tailgate would reduce drag. Some companies even sell tailgates with vents to "improve" aerodynamics. It turns out that with the gate closed, the bed is "full" of air and the lowest coefficient of friction is air moving past air. The same is true in other cases of fluid dynamics (e.g. the skin of a shark is covered in tooth-shaped "denticles" which hold water against the surface, creating less drag.) A hard and fast rule for engineers: when in doubt, copy mother nature.

 

[SeaGeo]

Closed will be less drag unless Rivian has an effective spoiler on the roofline (it doesn't look like anything more than a design flourish.)
Years ago an aero test (wind tunnel) of the pickup body showed that with the bed open, there is less drag if the tailgate is closed (not open.) It was a long held but mistaken belief that dropping the tailgate would reduce drag. Some companies even sell tailgates with vents to "improve" aerodynamics. It turns out that with the gate closed, the bed is "full" of air and the lowest coefficient of friction is air moving past air. The same is true in other cases of fluid dynamics (e.g. the skin of a shark is covered in tooth-shaped "denticles" which hold water against the surface, creating less drag.) A hard and fast rule for engineers: when in doubt, copy mother nature.

This is consistent with my understanding (though I heard them say that the "spoiler" is actually functional). Just curious how much of an impact they have seen with it open vs closed.

I've had some fun conversations over the years about bed open vs closed with people...

I didn't know about the shark skin. That's neat. Thanks!

 

[Attesan997]

Has anyone asked Rivian if they can share any data on the impact of the tonneau position on range? I'm inclined to leave mine open unless I have a reason to close it as a way to protect it from the elements.

I'd be surprised if its substantial. I'm no expert but if removing the plastic covers from the Gemini wheels on the Y is approx a 3-5% hit. I'd image keeping the cover open to be similar to no more than a few points more than that. The AT tires are in the 10-15% range so I'd wager is less of a hit than that.

Separately I'm curious as to what if any maintenance will need to be done to the cover or rolling mechanism. Based on that video yesterday from Chicago Auto Pros it appears debris rolled into the cover is going to have an impact on the mechanism over time.

 

[Zoidz]

TLDR from MotorTrend (you know what TLDR means if you Reddit):
"As expected, the results verified the wind tunnel data; trucks equipped with caps and tonneaus obtained solid improvements in fuel economy over open-bedded trucks. They varied from 4 to 10 percent, depending on the host vehicle and engine package."

Given the amount of range angst people have, it's probably worth keeping the tonneau closed for most people.

 

[RideAlong]

could just have the tailgate down -

 

[SeaGeo]

could just have the tailgate down -

Can't tell if you joking...

 

[Zoidz]

Wind Tunnel Video - Tailgate up vs down, and he mentions tonneau cover makes it even more efficient.

 

[SeaGeo]

Well, the next obvious question is whether theh had it open or closed for EPA testing...

 

[Attesan997]

Well, the next obvious question is whether theh had it open or closed for EPA testing...

I'd be surprised if it were open, the testing regiment had it in a mix of all purpose and conserve modes from what I recall. The 310+ rating I think is ideal, hopefully more on the Porsche Taycan end of ideal than the Telsa end. The quick math I've done in some of the first drive videos where I can see the efficiency screen, its seems pretty close to EPA.

 

[SeaGeo]

I'd be surprised if it were open, the testing regiment had it in a mix of all purpose and conserve modes from what I recall. The 310+ rating I think is ideal, hopefully more on the Porsche Taycan end of ideal than the Telsa end. The quick math I've done in some of the first drive videos where I can see the efficiency screen, its seem pretty close to EPA.

Agreed. Just hoping there may have been some conservatism built in there.

 

[louisdeg]

Close it to keep the snow off your tools.

 

[the long way downunder]

Well, the next obvious question is whether theh had it open or closed for EPA testing...

If it's standard equipment, it has to be installed (for weight and aero) and I assume "closed" is the default position (as with hood, windows and sunroof, if applicable.) I imagine the IPO docs or the earnings docs have to disclose the configuration of R1 used for EPA. As with my F-150 Hybrid for example, EPA 24/24 (now 23/23 for '22) was not the heavy config for max towing with luxury options and off-road tires or cruising at 75-85+ mph, so I don't gas when I look at the average 17-18 mpg per tank … : )
In my experience with Teslas, it's not the range or the Wh/mi, it's the charging curve and the locations of the Supercharger network.
What I want to see from EVgo, Electrify American, Rivian Adventure Network, etc. is a lot of charging pedestals everywhere. What I want from Rivian is to be able to stop with 10% and charge to 80% in 10 minutes (or whatever) at 210kW (or whatever) with no fuss (no crowding and queues, no battery problems that make me wait while the vehicle conditions itself and charges at 50kW.)
What I want to see from the US Govt is rows of 250kW and 350kW charging pedestals next to supermarkets and along freeway junctions. No need to hunt down a charging location behind a hotel parking lot somewhere and wait with three other people for your turn to wait for your car to balance and condition its battery to start charging. This solves the real problem of charging: finding a charging point when the vehicle is at 10% with confidence that there will be a charging point right there or even confidently run down to 5%. That's the problem with Tesla Superchargers today – while there are plenty of locations, unless your vehicle on your trip under the current weather conditions is at 10% right when you're near a Supercharger, you have to stop earlier … maybe at 20% … maybe at 40% because you know you can't get to the next Supercharger without risking nearly 0%. So you have to stop, even if it's only 150 miles. Then you have to guess how much to charge to reach the next Supercharger with a 10% margin of error. Hope the weather doesn't change. Hope there's no traffic delays. Crazy.

 

[SeaGeo]

If it's standard equipment, it has to be installed (for weight and aero) and I assume "closed" is the default position (as with hood, windows and sunroof, if applicable.) I imagine the IPO docs or the earnings docs have to disclose the configuration of R1 used for EPA.

THat's basically the gist of my question. I don't recall seeing any mention of it in the EPA docs. Who's to define what "default" is for a cover on a truck bed? WIndows, sunroof, and hood are totally different imo. There's also nothing that would have prevented them from using a conservative approach. I'm with you that I suspect that they had it closed though.

If it's standard equipment, it has to be installed (for weight and aero) and I assume "closed" is the default position (as with hood, windows and sunroof, if applicable.) I imagine the IPO docs or the earnings docs have to disclose the configuration of R1 used for EPA. As with my F-150 Hybrid for example, EPA 24/24 (now 23/23 for '22) was not the heavy config for max towing with luxury options and off-road tires or cruising at 75-85+ mph, so I don't gas when I look at the average 17-18 mpg per tank … : )
In my experience with Teslas, it's not the range or the Wh/mi, it's the charging curve and the locations of the Supercharger network.
What I want to see from EVgo, Electrify American, Rivian Adventure Network, etc. is a lot of charging pedestals everywhere. What I want from Rivian is to be able to stop with 10% and charge to 80% in 10 minutes (or whatever) at 210kW (or whatever) with no fuss (no crowding and queues, no battery problems that make me wait while the vehicle conditions itself and charges at 50kW.)
What I want to see from the US Govt is rows of 250kW and 350kW charging pedestals next to supermarkets and along freeway junctions. No need to hunt down a charging location behind a hotel parking lot somewhere and wait with three other people for your turn to wait for your car to balance and condition its battery to start charging. This solves the real problem of charging: finding a charging point when the vehicle is at 10% with confidence that there will be a charging point right there or even confidently run down to 5%. That's the problem with Tesla Superchargers today – while there are plenty of locations, unless your vehicle on your trip under the current weather conditions is at 10% right when you're near a Supercharger, you have to stop earlier … maybe at 20% … maybe at 40% because you know you can't get to the next Supercharger without risking nearly 0%. So you have to stop, even if it's only 150 miles. Then you have to guess how much to charge to reach the next Supercharger with a 10% margin of error. Hope the weather doesn't change. Hope there's no traffic delays. Crazy.

Pretty sure this is exactly the reason Rivian is making RAN closed to Rivian's in the short term. They want to provide QoS with capacity headroom and a reliable experience that doesn't rely on EA. EVGO doesn't really count IMO because their expansion is so focused on urban areas (which confuses me with their GM partnership).

 

[Bleo]

Obligatory old-timey looking Mythbusters video where this question + others are tested and addressed:

I'm not qualified to challenge their results.

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