Out of Spec Highway Range Test of Gen2 R1T dual Max - Nowhere near EPA

[shap]

Air resistance increases with the square of velocity, so I have some trouble believing that efficiency doesn't change when the force required to overcome drag increases by 47%. The more brick-shaped your vehicle is, the more it's affected by it vs rolling resistance and mechanical losses. Over about 45 mph drag dominates losses.

EVs aren't any more or less susceptible to that. It's more that the split between city and highway driving has a large impact on the actual numbers and it's more a problem with how often people pay attention. EVs see their ranges hit when driving faster than their EPA test speeds on highways, which are virtually always lower than actual traffic speeds, and situations where people need that 250 mile range are usually making highway trips. I can't say I've ever cared that getting 14 MPG driving 80 in a truck on a highway only allowed me to go 350 miles instead of the 500 miles it would have if it was getting its advertised 20 highway MPG. Nobody driving in stop and go city traffic ever cares about how terrible their mileage is because usually nobody is driving 200 city miles in one shot.

An EV buyer just sees '300 miles' and expects that to be road trip range, which it isn't. Since the EPA range number is a blend of city stop/go and highway driving, the harder a maker tries to game the tests to make the number go up, the more likely it is that the range depends on the proportion of more efficient city driving. Which then makes its highway performance look like absolute ass, since there's no real way to make it perform better at higher speeds without changing its aerodynamics.

I guess this is due the fact that ICE cars are low efficient car by definition. So the impact is much lower. It is obviously there but I do not feel it. Maybe 1mpg.

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[Donald Stanfield]

ICE has much less impact from high speed - much less than EV. For my X5 it does not really matters, 70mph or 85 mph. same 25-26 mpg efficiency.

That has more to do with Aero. The R1 series is a big blocky vehicle. My wife's i4M50 doesn't care if you go 85, the efficiency is pretty much the same. That's the difference between a low to the ground, sporty sedan and a brick with wheels.

 

[DayTripping]

The problem with aero drag is it is almost vertical curve. Drag goes up by the square of speed and HP required goes up by the cube.

So we need to either reduce frontal area, or improve drag coefficient. Since we can't shrink the size, all we can do is improve the drag where we can. On an R1T, a tonneau cover won't make much difference at 45 mph (since aerodynamic drag isn't as much of a factor) but at higher speeds it will definitely help.

Dropping to the lowest ride height will help. The tradeoff is that there can be additional tire wear (camber change) if you didn't set up your alignment for that setting.

Where I live, when my truck is on the highway, I am cruising at 75-85 mph most of the time. I plan to get an alignment in the lowest setting after I get my new tires on. I run in the lowest or low setting with my G1 quad motor.

For a truck, the Rivian has pretty good drag coefficient (Cd). Rivian claims .30 but AirShaper thinks it might be closer to .322. They basically scanned a 3D model and came up with that. What is interesting is one of the high pressure areas is at the top of the A pillar. That is where I have a lot of noise. Compare the R1T's .30 to my Model S of .208 and that is a huge difference. In general, the fact that AirShaper got so close to the factory's claim is quite good.

There could be a few issues with the model, wheel covers, etc, but close enough that Rivian is pretty accurate in their claim. Here is the video for those interested.

 

[shap]

That has more to do with Aero. The R1 series is a big blocky vehicle. My wife's i4M50 doesn't care if you go 85, the efficiency is pretty much the same. That's the difference between a low to the ground, sporty sedan and a brick with wheels.

Mine is X5 45e, not a small car. Also, electric motors become much less efficient with high RPM's, while mX5 has 8-speed transmission. BTW, I think the Porshe EV actually has 2 gears, which is why it has better efficiency on the highway. Not sure how Lucid does this.

 

[Electrified Outdoors]

ICE vehicles with an 18 gallon gas tank have A LOT more energy onboard than an EV with a 131 kWh battery like the gen1 large Rivian. The Rivian only carries the equivalent energy of about 4.5 gallons of gas. Because it’s so much more efficient it’s able to go hundreds of miles on that. An ICE on the other hand can tolerate a significant drop in efficiency because they are already horribly inefficient and have a ton more energy onboard so the loss can be spread and is less noticeable to the end user.

ICE still suffer significant loss in efficiency at high speeds, inclement weather, and extreme temps.

 

[greyboundary]

I haven't done a 2 hour+ sustained test, but my steady 30 min highway road trips consisntely go like this:

This is at 38 degrees, heat on, 72-75mph, Goodyear ATs (the "all seasons"), dual max gen 2. The efficiency picks up quickly after these first 10min or so and settles around mid 2s and often a bit over, and just stay put as long as I'm driving.

IMO, that's solid and I'm extremely satisfied with the winter trips I've done. These one reviewer one run clickbait tests almost just feel like an attempt to shoot ourselves in the foot as far as EV perception goes.

 

[shap]

I haven't done a 2 hour+ sustained test, but my steady 30 min highway road trips consisntely go like this:

This is at 38 degrees, heat on, 72-75mph, Goodyear ATs (the "all seasons"), dual max gen 2. The efficiency picks up quickly after these first 10min or so and settles around mid 2s and often a bit over, and just stay put as long as I'm driving.

IMO, that's solid and I'm extremely satisfied with the winter trips I've done. These one reviewer one run clickbait tests almost just feel like an attempt to shoot ourselves in the foot as far as EV perception goes.

Same 20" GY tires, on conserve at 75 give me 2.0. 7C outside temperature. No idea how you get these numbers. But happy for you.

Yesterday on my R1T QM, Large, charged to 100% (316 miles on display) I drove from Austin to Houston. 187 miles. Got there with 15% left (45 miles). Heat on. 75-85 mph. I think I averaged 1.78 m/kWh. This is real word driving in Texas.

 

[greyboundary]

Same 20" GY tires, on conserve at 75 give me 2.0. 7C outside temperature. No idea how you get these numbers. But happy for you.

Yesterday on my R1T QM, Large, charged to 100% (316 miles on display) I drove from Austin to Houston. 187 miles. Got there with 15% left (45 miles). Heat on. 75-85 mph. I think I averaged 1.78 m/kWh. This is real word driving in Texas.

What gen / motor setup?

Also, I'm sure you've heard it a million times, but going 85 doesn't really help. Not just exponentially increasing power demand, but even the trip time. I've done this one particular 2h trip in my Lotus at both 72 and mid 80s. The latter certainly feels fast, absolutely destroys fuel, but doesn't even save that much time.

 

[shap]

What gen / motor setup?

Also, I'm sure you've heard it a million times, but going 85 doesn't really help. Not just exponentially increasing power demand, but even the trip time. I've done this one particular 2h trip in my Lotus at both 72 and mid 80s. The latter certainly feels fast, absolutely destroys fuel, but doesn't even save that much time.

I mentioned R1T QM, so gen 1. Speed is not only about getting faster but also flow with the traffic. 75 is almost a minimum posted limit on TX highways. Unfortunately speed affects mostly EVs and not ICE (1 mpg difference on my X5 between 70 and 85 mph).

 

[Bar_Down]

I mentioned R1T QM, so gen 1. Speed is not only about getting faster but also flow with the traffic. 75 is almost a minimum posted limit on TX highways. Unfortunately speed affects mostly EVs and not ICE (1 mpg difference on my X5 between 70 and 85 mph).

I've found traffic is the biggest wildcard to road trip results. However, regarding driving at high speeds (e.g. 80 or 85) actually making trips longer... that has not been my experience. I have found that arriving at DC fast chargers with 5-10% SOC and unplugging at 70% (assuming you can then make it to another charger) and then driving at 80 or 85 to that next charger is the way to get lowest total trip durations. Yes, I end up charging more often or more (because I've used more energy traveling at higher speeds), but the time savings of driving 10-15 mph faster over long distances more than makes up for the longer charging. The overall difference is meaningful (e.g 1 hr for a 550 mile trip)

 

[greyboundary]

I mentioned R1T QM, so gen 1. Speed is not only about getting faster but also flow with the traffic. 75 is almost a minimum posted limit on TX highways. Unfortunately speed affects mostly EVs and not ICE (1 mpg difference on my X5 between 70 and 85 mph).

Dual motor is the most efficient across both gens, and gen 2 motors were also supposed to be more efficient. That's particularly why I went with this setup, previously having had the "fast" option and realizing range is a far better feature. Plus, this thing still moves plenty fast for a pickup.

Power demand in relation to speed is just a straight up energy principle and it applies to both equally. Your x5 maybe has less efficiency than it should at slightly slower speeds, has favorable gearing, or something else. My Lotus has a wind tunnel designed body and the difference between 72 and 85 is slaughter, as it has been in all my gas cars.

(Or your meter is lying. I’ve definitely been in ICE cars that the actual consumption rate according to the miles / refill volume did not match the dashboard stat)

 

[DayTripping]

Dual motor is the most efficient across both gens, and gen 2 motors were also supposed to be more efficient. That's particularly why I went with this setup, previously having had the "fast" option and realizing range is a far better feature. Plus, this thing still moves plenty fast for a pickup.

Power demand in relation to speed is just a straight up energy principle and it applies to both equally. Your x5 maybe has less efficiency than it should at slightly slower speeds, has favorable gearing, or something else. My Lotus has a wind tunnel designed body and the difference between 72 and 85 is slaughter, as it has been in all my gas cars.

(Or your meter is lying. I’ve definitely been in ICE cars that the actual consumption rate according to the miles / refill volume did not match the dashboard stat)

Motor efficiency will almost be irrelevant compared to aerodynamic drag at high speeds. If I was driving 50-60mph, I might care if I was dual motor, or quad. At 80 mph on most TX highways, it really isn't going to matter much. The power used to overcome the aerodynamic drag is going to dwarf the slight efficiency gains. At slower speeds, like on the EPA test, they will show up.

When you have aerodynamic drag at 75 mph likely at a ratio of 4 times greater than all other drag, a slight motor efficiency gain is more of an academic point than practical one in my usage. Not saying it doesn't matter, but I'd spend my money on aerodynamic improvements for better range at the speeds my traffic is normally flowing (when not stuck in bumper to bumper rush hour).

 

[shap]

100% agree. I guess the next real challenge for industry - how we can make batteries charge faster and in more consistent way. If I could get ~100kW in 15 minutes, this would be good enough.

Yesterday, I charged from 5% to 74%. It took 38 min. The battery got to 46C. But the AC was not engaged till I started to drive, and then it started at full throttle till temp. went to 41C.
Why Rivian did not engage AC while it was charging - no idea.

 

[greyboundary]

Motor efficiency will almost be irrelevant compared to aerodynamic drag at high speeds. If I was driving 50-60mph, I might care if I was dual motor, or quad. At 80 mph on most TX highways, it really isn't going to matter much. The power used to overcome the aerodynamic drag is going to dwarf the slight efficiency gains. At slower speeds, like on the EPA test, they will show up.

When you have aerodynamic drag at 75 mph likely at a ratio of 4 times greater than all other drag, a slight motor efficiency gain is more of an academic point than practical one in my usage. Not saying it doesn't matter, but I'd spend my money on aerodynamic improvements for better range at the speeds my traffic is normally flowing (when not stuck in bumper to bumper rush hour).

When you say there’s more drag, it demands more power: where do you suppose it comes from? The efficiency of the motors–the proportion of that the energy that goes in and mechanical force out to provide said power–absolutely matters.

It’s not whether motor efficiency matters more or less than drag if the discussion is about why your gen1 quad isn’t seeing the same range as a gen2 dual (with the same aerodynamics). Rivian literally lists officially different ranges for a reason.

(That said I’ve only seen them refer to it being “more efficient” and am not sure in what circumstances or in what ways)

 

[DayTripping]

I am not saying it doesn’t matter. I am saying in my use case, aerodynamic improvements would matter more. So far it seem that the people that are driving faster (than EPA testing) with G2 trucks on the highways aren't seeing anywhere near the gains you might be led to believe based on the EPA numbers. There is a good thread here already about someone who went from a G1 quad to a G2 dual motor and is seeing almost the same efficiency numbers. Here is a good thread for reference.

https://www.rivianforums.com/forum/...-pack-efficiency-and-charging-analysis.37135/

I drove the demo Rivians at my SC over the same routes, with both the G1 & G2 trucks/SUVs before buying my G1 quad. I didn't see any noticeable efficiency differences there. A lot of manufacturers have learned how to game the EPA test cycles anyway. Tesla is notoriously good at that and I am sure it wasn't lost on Rivian since so much emphasis is placed on range for EVs.

I'd love to see an independent test of a G2 tri motor running simultaneously on the same roads as a G1 quad motor at 76-80 mph until the battery is depleted (or at least 150-200 miles) with the same size pack. I am betting there won't be a huge difference in energy efficiency, and likely far less than what you might believe based on the Rivian EPA numbers.

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