R2 Highway Efficiency Test: 80 MPH vs 70 MPH Changed Everything

[tivoboy]

Noting that Air is 14% less dense at 5,000 ft than Sea Level. That translates into about an 8% benefit at high altitude at 75 mph (depending on vehicle). Beware colorado 70 mph range tests!

ok you are DEFINITLY CROSSING THE BRIDGE..the answer to most things in life is ALWAYS
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[wiley one]

Haha, The ant eater, aardvark edition! .

Everyone thinks it's the frontal area. The actually, the biggest drag contributor is the rear end. It's all the air separation due to the blunt end. This is why so many vehicles, especially EVs have sloping back (e.g., Model Y). The front is actually managed quite nicely for a squared off facia and the hood. Rivian has spent lot of time for both R1 and R2 to manage how the air flows around it.

R2 is better than R1S with the split high rear wind deflector (and subtle sloped top aft end), compared to the R1S, which has nothing. At least on R1T, there is a roof end wing trying to manage the airflow behind the cab and how it interacts with the bed.

Gen 2 aero cone.

 

[Jeremy3292]

Tom just did a 70 mph test and got 259 miles but didn’t actually hit empty, so probably 265 miles. HOWEVER, it was uphill (2,000 feet) most of the way with 15 to 20 mph crosswinds. He said its a 280+ miles vehicle in decent conditions and terrain and can hit 300 miles going 70 mph in great conditions. Reminder this was also with the 20” AT tires too.

For reference Kyle at OOO did 298 miles to truly empty on the Juniper Model Y AWD at 70 mph. Model Y will win at higher speeds 70+ due to superior aero, they’ll be the same around 60-70 mph, and R2 will win under 60 mph due to the larger battery pack.

 

[mkhuffman]

@ksurfier - did you weigh the tires?

 

[ksurfier]

@ksurfier - did you weigh the tires?

No, just kicked them...everyone was looking at me funny...

But ABRP shows the following (only a ~5% difference betweem 20" and 21")
R2 at 80 mph can travel ~190 miles (2.16 MPK)
R2 at 75 mph can travel ~200 miles (2.3 MPK)
R2 at 70 mph can travel ~213 miles (2.45 MPK)
R2 at 66 mph can travel ~225 miles (2.6 MPK)
R2 at 58 mph can travel ~250 miles (2.85 MPK)

 

[Glembi2]

Haha, The ant eater, aardvark edition! .

Everyone thinks it's the frontal area. The actually, the biggest drag contributor is the rear end. It's all the air separation due to the blunt end. This is why so many vehicles, especially EVs have sloping back (e.g., Model Y). The front is actually managed quite nicely for a squared off facia and the hood. Rivian has spent lot of time for both R1 and R2 to manage how the air flows around it.

Ha! Ya got me thinking of Ricky Bobby and the slingshot.

Two R2s traveling with one in the slipstream of the other must be wildly efficient.

and if you get pulled over, say you were not tailgating but drafting.

 

[Jeremy3292]

No, just kicked them...everyone was looking at me funny...

But ABRP shows the following (only a ~5% difference betweem 20" and 21")
R2 at 80 mph can travel ~190 miles (2.16 MPK)
R2 at 75 mph can travel ~200 miles (2.3 MPK)
R2 at 66 mph can travel ~225 miles (2.6 MPK)
R2 at 58 mph can travel ~250 miles (2.85 MPK)

These are way too low…Tom did 3 miles per kWh at 70 mph up a hill 2,000 feet with crosswinds.

 

[ghostowl]

Also, keep in mind temperature matters a bunch. Hotter temperatures will be more efficient. Colder temperatures less efficient. The cooler the air, the more dense it is, the more it decreases efficiency. Gas cars lose 10-20% range when its below freezing _despite_ the fact that cold air is better for ICE engine efficiency.

The air flow issues are also why towing effects range so much. If you add twice as much air drag, you get half the range. The same is true of ICE vehicles, people just don't make a big deal of it.

 

[UnsungZero_OldTimeAdMan]

When does Rivian release a nosecone attachment for higher speed road trips??

A parabolic Lexan cone, that places the car completely in its wake, would be more effective. Half of a cone to be precise.

 

[ksurfier]

These are way too low…Tom did 3 miles per kWh at 70 mph up a hill 2,000 feet with crosswinds.

You may be right...TexasBob had 250 miles range at 70 mph...which implies 2.84 MPK. But Tom's high elevation definittely needs to be accounted for (reduce by ~10% at least if it were at sea level, so ~2.7 MPK).

 

[Jeremy3292]

You may be right...TexasBob had 250 miles range at 70 mph...which implies 2.84 MPK. But Tom's high elevation definittely needs to be accounted for (reduce by ~10% at least if it were at sea level, so ~2.7 MPK).

5% at best for the altitude he was at, definitely not 10%. And you ignored the uphill and crosswinds and colder weather and he still got 265 miles on 20” AT.

 

[ksurfier]

5% at best for the altitude he was at, definitely not 10%. And you ignored the uphill and crosswinds and colder weather and he still got 265 miles on 20” AT.

So 21" might get 278 miles range then, not a whole lot more...implying 3.16 MPK at 70 mph? TexasBob has 250 miles so that doesn't work unless you reduce by 11%...sea level vs 5,000 feet is around 20% difference in air density (0.062 #/cf vs 0.052 #/cf)...air temp will also play a big role...

 

[1oki]

Did some crude gpt calculations on incorporating charge times and distance traveled to see if charging more at 80 mph is worth it at any distance. Assumptions made: 30min 10-80% charge time, efficiency static at 3.0 mi/kwh for 70mph, and 2.35 mi/kwh for 80mph speed. Starting at 100% SOC then charging 10 to 80% on subsequent charges.

Distance	70 mph Drive	70 mph Charge	70 mph Total	80 mph Drive	80 mph Charge	80 mph Total	Time Saved at 80 mph
100 mi	1h 26m	0m	1h 26m	1h 15m	0m	1h 15m	11m
200 mi	2h 51m	6m	2h 57m	2h 30m	3m	2h 33m	24m
300 mi	4h 17m	25m	4h 42m	3h 45m	24m	4h 09m	33m
400 mi	5h 43m	38m	6h 21m	5h 00m	45m	5h 45m	36m
500 mi	7h 09m	54m	8h 03m	6h 15m	1h 06m	7h 21m	42m
600 mi	8h 34m	1h 11m	9h 46m	7h 30m	1h 27m	8h 57m	49m
700 mi	10h 00m	1h 27m	11h 28m	8h 45m	1h 48m	10h 33m	55m
800 mi	11h 26m	1h 44m	13h 10m	10h 00m	2h 09m	12h 09m	1h 01m
900 mi	12h 51m	2h 00m	14h 52m	11h 15m	2h 30m	13h 45m	1h 07m
1000 mi	14h 17m	2h 17m	16h 34m	12h 30m	2h 51m	15h 21m	1h 13m
1100 mi	15h 43m	2h 33m	18h 16m	13h 45m	3h 12m	16h 57m	1h 19m
1200 mi	17h 09m	2h 50m	19h 59m	15h 00m	3h 33m	18h 33m	1h 26m
1300 mi	18h 34m	3h 06m	21h 41m	16h 15m	3h 54m	20h 09m	1h 32m
1400 mi	20h 00m	3h 23m	23h 23m	17h 30m	4h 15m	21h 45m	1h 38m
1500 mi	21h 26m	3h 39m	25h 06m	18h 45m	4h 36m	23h 21m	1h 45m

 

[mkhuffman]

No, just kicked them...everyone was looking at me funny...

But ABRP shows the following (only a ~5% difference betweem 20" and 21")
R2 at 80 mph can travel ~190 miles (2.16 MPK)
R2 at 75 mph can travel ~200 miles (2.3 MPK)
R2 at 70 mph can travel ~213 miles (2.45 MPK)
R2 at 66 mph can travel ~225 miles (2.6 MPK)
R2 at 58 mph can travel ~250 miles (2.85 MPK)

ABRP uses estimated data, which isn't accurate. I know, Rivian owns ABRP. For some reason, ABRP doesn't have special access to Rivian data. It has been proven time and time again.

I love ABRP and use it when planning for every trip I take. But it uses made up reference data you need to confirm with your actual vehicle. It was true with my Mach-e, and is true with my R1T.

 

[3wisemonkeyz]

R2 is better than R1S with the split high rear wind deflector (and subtle sloped top aft end), compared to the R1S, which has nothing.

i sense an aftermarket opportunity for Gen1/2 and hopefully built into Gen3

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