https://imgur.com/a/ndFgXxU
(Idk if this is the right place. I tried posting to askEngineering but I don’t have enough posts to participate. And on r/cars i think people would be to harsh if I'm wrong, i'm fragile)
When looking into the car’s range statistics to know if battery is an issue for the Nurburgring (Nürburgring is 20.832km) (I’ve done a lot of research on the road and I'm 100% certain the skirt will function). And initially I was dismayed; according to this supposed “accurate” brochure from McMurtry automotive themselves in a Schmee150 video (later I will use a number from the website itself). The range in f1 mode at Silverstone GP would just be 11.782km with voltage sag. That’s terrible. And I had already done arc calculations for every turn at the Nurburgring assuming it had the range in f1 mode. Getting a time of 5:09.69 (3.5G) to 5:14.05 (3G) depending if 3.5G is the new baseline maximum at low speeds or not.
So I thought “I need a real world comparison”. So I got the volkswagen idr to use its statistics to find the true range numbers. (And then the Rimac Nevera later to compare) The Volkswagen IDR had a 45kWh battery and used 24.7kWH (of which 9.7% was energy regenerated) for a time of 6:05.33 minutes. This is 54% of the entire battery used with all that downforce drag included. Which is 1.185kWh/km.
So to get a number comparison I would imagine it being at full power for the whole lap. So seeing as the idr used 54%. Ill multiply the full power result by 52% because of lower drag, and ill use the same time for starters.
So putting the Murtry into LMP2 mode: 650hp with 75% downforce (45kw fan). The fan energy has been calculated at a maximum of 60kW. So 650 x 745.7= 484.7kW | 484.7 x 0.101389hours (which is 6:05.00, yes its 33 milliseconds slower in reality but for some reason i did that but the difference is so minor so whatever) which equals to 49.14kWh | (49.14 x 0.52)= 25.55kWh | 25.55 x 9.7% =2.47kWh | 25.55 - 2.47= 23.08kWh | 23.08+4.56(fan)= 27.64kWh in reality | 1.326kWh/km
(I decided to add the fan at the end because the energy regenerated for the idr wasn’t with a fan included. Now the Murtry has crazy braking performance, 4G maximum with spoiler (according to info available currently)down to 3G constant baseline across all speeds and regenerates up to 200kW at maximum. I can’t calculate what energy it will regenerate since idk the exact numbers it will be going at before entering the turns, but I presume it would regenerate slightly less energy than 9.7% because of its braking performance and higher corner speed, but this is accurate enough and is satisfactory.)
1.185kWh/km. IDR
1.326kWh/km McMurtry
This is 12% more energy used which is reasonable. But now we’ll calculate using the brochure and the website for LMP2 mode.
From my interpretation, the brochure says 6.5 laps at lmp2 mode. Which is 100kWh in 38.291km. Which is 2.611kWh/km. The website displays a maximum of 50km in lmp2 mode, so 100kWh in 50km is 2kWh/km.
This is 168% to 220% times more energy used for a 35hp difference (plus a small amount of fan) on a car with a much smaller profile and drag. This seems unreasonably inefficient. The McMurtry is at the pinnacle of electric vehicle technology.
Now we’ll go to f1 mode: 1000hp and 100% downforce (60kW fan). We’ll use the 919 Evo’s time just to use a real number 5:19.54 minutes (0.08876 hours). The energy recovered would be less in reality I believe but i’ll use the same number, just imagine it being slightly bigger: 1000 x 745.7= 745.7kW | 745.7 x 0.08876= 66.18kWh | 66.18 x 0.52 = 34.413kWh | 34.413 x 0.097= 3.338kWh | 34.413-3.338+5.32= 36.39kWh in reality | 1.747kWh
Now we’ll use the dreaded brochure: 100kWh in 11.782km = 8.487kWh/km | 8.487 x 20.832 (Nurburgring length) = 176.801kWh in 20.832km. Now depending how you interpret the brochure, the 52% could already be in there, but ill add the 52% anyways. [176.801kWh & 8.487] times 52% is 91.936kWh | 4.413kWh/km !!!! To give a comparison now, let's see the Rimac Nevera.
The Rimac Nevera:
- 1914 hp
- 5071 lbs
- 120kWh battery pack
- Used 42kWh at the Nürburgring (7:05.298)
- 2.016kWh/km
- 10.39 MPGe
The McMurtry Spéirling Pure:
- 1000 hp
- 2971 lbs
- 100kWh battery pack
- 176.81kWh??? That’s 4.209x the Nevera in energy usage.
- 8.487kWh/km
- 2.46 MPGe
OR
- 91.936kWh??? That’s still 2.18x the Nevera.
- 4.413kWh/km
- 4.74 MPGe
Even if we interpret the brochure as the 60kWh battery pack, its still comes out at 5.093kWh/km or 4.11 MPGe. The reality at f1 mode should be 36.395kWh -1.747kWh/km - 11.69MPGe for 5:19.34
The Pure has 914 less horsepower, weighs a whole 2094.76 pounds less. And completes the lap (according to my work) 115.608 SECONDS FASTER than the Rimac Nevera. Because the fan system allows it to do turns at incredible speeds with zero drag, and because it weighs 2094.76 pounds less, it requires much less energy in acceleration overall because its exit speed is much higher and it’s way lighter.
Referring back to the picture of the graph you can see this difference. Am I doing something wrong? Am I crazy to think this is impossibly inefficient for the numbers McMurtry Automotive is giving us? If i’m wrong, where is all this energy going? Because the fan barely draws power. The McMurtry is at the pinnacle of battery technology, motor technology, and the thermal load is lower. This shouldn’t be possible. All I can see is my numbers are the truth. If they’re like 95% accurate, why lie of range statistics this badly? This hurts the brand's image as it’s one of the main things haters say about the car is the range. But from this, its range is incredible for the performance. Are buyers brought in on this secret? Just like the road legal variant they’ve made zero mentions of which also hurts the image of the brand when not mentioning it (for 200kgpb you can make it road legal through Lazante, a photo exists reading the words “road conversion prototype” on it at GoodWood when the pure was on display).
So what do you think? Am I validated in my logic?