Gravity 75 mph Range

[boydracing]

If you have the patience, it is in this OOS 2-hour video:

I didn't mark the spot where they talk about it, but I think it was when they are going through the configurator and selecting the wheels.

BTW - I put Hankook Ion tires on my Mach-e, and they are great. I saw a 7% highway range improvement over the OEM tires. I find it very interesting that OOS/Lucid praise how well they handle, as I think they are more slick than the OEM tires they replaced, but certainly the efficiency is way better. I like them, though. They are very quiet.

I checked Tire Rack and they don't carry sizes that fit any of the wheels on the Gravity. So the base set must be an OEM special for Lucid, which I am sure will show up on Tire Rack eventually.

I am also going with the 20" wheels on Hankooks just for the snow performance (best of the bunch) and good for EV use. It snows here in Park City.

 

[boydracing]

I noticed that adding the third row knocks 3% off the EPA range estimate. This is very surprising., because I didn't think those seats would be very heavy. What happens to the range when you have seven people in the car?

Luckily for the range I am concerned about, steady state highway, weight has a minor impact, and the extra row should not impact range at speed.

In the OOS Gravity first drive video (not the podcast posted above), they discuss EPA range and how important keeping the weight down was for meeting the 450-mile range result. To me that means the city driving component is a significant contributor to the 450-mile range result, which consequently likely means highway range will be even worse than expected. Now I am second guessing the 80%, factor and maybe @hmp10 is right about it being closer to 2.4 mi/kWh. I hope this is not the case.

However, 80% of 437 is 350 miles, which is still good for me.

View attachment 25358

Does anyone have an answer if you order the 3rd row, can you remove and still be flat like not ordering the third row. I have a 55 lb and 14 lb dog that needs room in the back. I saw Kyle's video and when they stow the third row, it is very uneven.

 

[borski]

Does anyone have an answer if you order the 3rd row, can you remove and still be flat like not ordering the third row. I have a 55 lb and 14 lb dog that needs room in the back. I saw Kyle's video and when they stow the third row, it is very uneven.

You cannot remove the third row. I don't know about Kyle's video, but when the third row stows it is intended to be completely flat, and is intended to be level with the rest of the stowed cabin. The idea is that the entire cabin can be one flat space, for loading objects.

 

[hmp10]

Does anyone have an answer if you order the 3rd row, can you remove and still be flat like not ordering the third row. I have a 55 lb and 14 lb dog that needs room in the back. I saw Kyle's video and when they stow the third row, it is very uneven.

I saw a video recently that raised this point, and the narrator said Lucid told him there would be an accessory cover that filled in that gap to create a flat floor for things such as putting a camping mattress in the back.

 

[Elfin]

One thing I've been curious about is why cars drops so much efficiency at 80mph. Here is the Out of Spec data from their 10% challenge (80mph) and 70mph range test
2025 Air GT 4.3mi/kwh@70mph 2.9mi/kwh@80mph 48% increase in energy
2025 Taycan 3.7mi/kwh@70mph 2.7mi/kwh@80mph 37% increase in energy
2024 Model 3 LR RWD 4.9mi/kwh@70mph 3.3mi/kwh@70mph 42% increase in energy
This seems higher than one would expect even if all losses are aerodynamic drag! (80/70)^2 = 31% increase.
While typing this I think I may have figure it out... The 80mph number is power delivered from charger so it includes charging losses while the 70mph is efficiency from the battery. The difference still seems large.

My prediction for 70mph range
511mi for Lucid Air GT at 70mph
20% more frontal area
20% higher Cd
4% bigger battery
15% increase in energy 75 vs 70
511/1.2/1.2*(123/118)*(70/75)^2 = 322 miles
Hope it's better than that so I'm going to change my guess to 350mi

 

[hmp10]

One thing I've been curious about is why cars drops so much efficiency at 80mph.

Aerodynamic drag increases exponentially with speed. A doubling of speed, for instance, increases the drag fourfold. At highway speeds, aerodynamic drag becomes the single biggest force resisting the car's forward motion.

Have you ever stuck the flat of your hand out of a car window on the highway and felt the wind almost rip your arm out of its socket? Now, multiply the surface of your hand by the frontal area of your car and you'll get some sense of what your car is pushing against.

That's why Lucid spends so much time and effort trying to shave every little bit of frontal area off its cars and whittle away at the drag coefficient every way possible. It's one of those areas in which even seemingly insignificant differences can yield very significant differences in outcomes.

 

[Elfin]

Aerodynamic drag increases exponentially with speed. A doubling of speed, for instance, increases the drag fourfold. At highway speeds, aerodynamic drag becomes the single biggest force resisting the car's forward motion.

Have you ever stuck the flat of your hand out of a car window on the highway and felt the wind almost rip your arm out of its socket? Now, multiply the surface of your hand by the frontal area of your car and you'll get some sense of what your car is pushing against.

That's why Lucid spends so much time and effort trying to shave every little bit of frontal area off its cars and whittle away at the drag coefficient every way possible.

Yes, my question was why the efficiency drops more than the aerodynamic drag formula suggests it should.
One would expect a 31% increase in energy consumption per mile due to aerodynamic drag at 80mph vs. 70mph.
I think part of the answer is that OOS measures efficiency from the charger at 80mph and efficiency from the battery at 70mph.

 

[hmp10]

Yes, my question was why the efficiency drops more than the aerodynamic drag formula suggests it should.
One would expect a 31% increase in energy consumption per mile due to aerodynamic drag at 80mph vs. 70mph.
I think part of the answer is that OOS measures efficiency from the charger at 80mph and efficiency from the battery at 70mph.

Oh, now I see what you were getting at.

I'm no engineer, so I had to resort to the internet where I found this:

"At 80 mph, the drag is approximately 36% higher than at 70 mph because 80^2 / 70^2 = 6400 / 4900 = 1.306."

 

[momo3605]

That's why Lucid spends so much time and effort trying to shave every little bit of frontal area off its cars and whittle away at the drag coefficient every way possible. It's one of those areas in which even seemingly insignificant differences can yield very significant differences in outcomes.

That’s why Lucid does the worst comparatively at 80mph? Look at the numbers posted…Lucid loses more range at 80mph than the others.

Not sure Lucid is doing anything special to improve the situation. For whatever reason, Lucid is more negatively affected by speed variances than other cars, and I don’t have a good answer for it

 

[hmp10]

Not sure Lucid is doing anything special to improve the situation. For whatever reason, Lucid is more negatively affected by speed variances than other cars, and I don’t have a good answer for it.

I don't have a good answer, either.

All I know is that fluid dynamics is a very complicated science with a huge number of variables at play. I wonder if some element of the car's design contributes to a lower Cd at one speed but can go in the opposite direction at a higher speed? If so, maybe Lucid chose to reach for the best Cd for the range of speeds most often driven? (While most of my long-distance driving is at 80-85 mph, the great bulk of even my sprightly driving is at speeds below 70 mph. And I suspect that's the case for a lot of people.)

As for Lucid not doing anything special, I'm pretty sure they did. For the Air they hired an aerodynamicist from Red Bull Racing and developed a novel Venturi cooling air intake design and state-of-the-art narrow headlight modules, to name just two I can remember. Those things carried over the the Gravity in addition to novel Gravity features such as the unusual rear roof wing.

 

[colmode]

Aerodynamic drag increases exponentially with speed. A doubling of speed, for instance, increases the drag fourfold. At highway speeds, aerodynamic drag becomes the single biggest force resisting the car's forward motion.

Have you ever stuck the flat of your hand out of a car window on the highway and felt the wind almost rip your arm out of its socket? Now, multiply the surface of your hand by the frontal area of your car and you'll get some sense of what your car is pushing against.

That's why Lucid spends so much time and effort trying to shave every little bit of frontal area off its cars and whittle away at the drag coefficient every way possible. It's one of those areas in which even seemingly insignificant differences can yield very significant differences in outcomes.

Aerodynamic/hydrodynamic drag increases roughly quadratically with speed (n^2); not anywhere close to exponentially (B^n). If it was exponential we wouldn't have airliners flying at 500kt, nor probably any rockets lifting anything into space. Jumping from altitude without a parachute might be survivable though.
Also, when saying that something is proportional to B^n you kind of have to say what B is. There's usually a big difference between 2^10 (1024) and 10^10 (10,000,000,000) of something.

 

[hmp10]

Aerodynamic/hydrodynamic drag increases roughly quadratically with speed (n^2); not anywhere close to exponentially (B^n). If it was exponential we wouldn't have airliners flying at 500kt, nor probably any rockets lifting anything into space. Jumping from altitude without a parachute might be survivable though.
Also, when saying that something is proportional to B^n you kind of have to say what B is. There's usually a big difference between 2^10 (1024) and 10^10 (10,000,000,000) of something.

Sorry, I confused exponential with quadratic. It's been over half a century since I sat in an algebra class.

But doesn't it still mean that aerodynamic drag quadruples with a doubling of speed?

 

[Steveinarizona]

Actual question: why get low-profile summer tires on an SUV? Doesn’t it pretty much defeat the purpose of an SUV?

Not if you need additional interior space that cannot be achieved in a sedan and/or you are getting old and it is getting increasingly hard to climb down into and then out of a Lucid Air and you are staying far away from off roading. The summer tires would maximize performance (local weather permitting) albeit not like that of an Air.

 

[colmode]

Sorry, I confused exponential with quadratic. It's been over half a century since I sat in an algebra class.

But doesn't it still mean that aerodynamic drag quadruples with a doubling of speed?

View attachment 27194

Yes, your example is correct, and it was pretty clear that you meant n^2. It's just that an exponential curve rises a lot faster than a quadratic one, and engineers get all twitchy when they see the common misuse of "exponentially" to just mean "a lot". Sorry for the OT. Need entertainment while waiting an exponentially long time for this car.

 

[hmp10]

Not if you need additional interior space that cannot be achieved in a sedan and/or you are getting old and it is getting increasingly hard to climb down into and then out of a Lucid Air and you are staying far away from off roading. The summer tires would maximize performance (local weather permitting) albeit not like that of an Air.

This interchange between you and @borski is like a time warp for me.

@borski's question is me 30 years ago. Your answer is me today.

Ah, the waters that have flowed under those bridges in the interim . . . .

 

[hmp10]

The summer tires would maximize performance (local weather permitting) albeit not like that of an Air.

That was my assumption, too. However, I can't get two comments from the recent Gravity test drive videos out of my mind.

One was Kyle Conner's remark that the Gravity might actually handle better than the Air. (And earlier in the day of the test drive he had returned an Air on which he just put 15,000 miles, so it was almost a head-to-head comparison.)

The other was Jason Cammisa's assertion that the Gravity actually raises the specter of making sports cars obsolete. (Cammisa was driving the Gravity that shot around a highway exit like a bullet on a centrifuge tether in front of the Gravity Conner was driving.)

I can't quite get my head around these observations, but I still wake up every morning asking, "could it just be possible?"

 

[Wulf0123]

Does anyone have an answer if you order the 3rd row, can you remove and still be flat like not ordering the third row. I have a 55 lb and 14 lb dog that needs room in the back. I saw Kyle's video and when they stow the third row, it is very uneven.

When I viewed it in vegas the employee said you could remove the 3rd row. Unfortunately I couldn't see how you could do it easily and he couldn't show me because it was an executive's car. But also when it's stowed it's entirely flat because it goes under the sub-trunk's cover. Any issues you see in Kyle's video is either from testing or pre-production imo. I got no confirmation on the gap between seats but also forgot to ask.

 

[hmp10]

When I viewed it in vegas the employee said you could remove the 3rd row. Unfortunately I couldn't see how you could do it easily and he couldn't show me because it was an executive's car. But also when it's stowed it's entirely flat because it goes under the sub-trunk's cover. Any issues you see in Kyle's video is either from testing or pre-production imo. I got no confirmation on the gap between seats but also forgot to ask.

I think the semantics get confusing. When Lucid says the rear rows fold to form a flat floor, they do not mean in the sense that a piece of plywood is flat. What they really mean is that all the seats fold to the same level.

Note where the yellow arrow is pointing in the picture below. As the third row stows backward into the rear of the car, this footwell gap is left between the motor/axle hump and the folded second row seats. It is to cover this gap that Lucid says they will offer an optional accessory panel.

I know this is a late prototype car, but I think the Gravity is well past the development point at which they would still be fundamentally redesigning the seat folding configurations.

 

[borski]

This interchange between you and @borski is like a time warp for me.

@borski's question is me 30 years ago. Your answer is me today.

Ah, the waters that have flowed under those bridges in the interim . . . .

This is an extremely fair point, to both of you. Age makes a difference, and at my spry 37, especially having lost 60 lbs over the last year, I want the smallest and lowest car I can find that goes fast.

But post hip replacement and with arthritis, my feelings very well may change haha

(I’m hypermobile, in the ehlers-danlos style but without an official diagnosis, so I’m prone to joint dislocations. Two shoulder surgeries so far, and I’m gonna be a creaky old man, I just know it lol)

 

[borski]

I think the semantics get confusing. When Lucid says the rear rows fold to form a flat floor, they do not mean in the sense that a piece of plywood is flat. What they really mean is that all the seats fold to the same level.

Note where the yellow arrow is pointing in the picture below. As the third row stows backward into the rear of the car, this footwell gap is left between the motor/axle hump and the folded second row seats. It is to cover this gap that Lucid says they will offer an optional accessory panel.

View attachment 27205

I know this is a late prototype car, but I think the Gravity is well past the development point at which they would still be fundamentally redesigning the seat folding configurations.

They do mean piece-of-plywood flat. It is a perfectly flat cabin with all the seats down. The gap does exist, hence the future accessory, but from trunk entry all the way through the cabin the level is the same, with only the gap.