Lowest Cd of Production Car
 

Lightyear has just released the results of their recent windtunnel tests. :cool:

A record-breaking drag coefficient (Cd of 0.20) has been reached. It's built to perform on energy efficiency. Read more on the Lightyear website News section.

What do you think? Will other EV's follow in striving towards energy efficiency?

Other EVs aside from tesla are all based on gas burner or gas burner hybrid bodies and they just don't need to be all that aerodynamic.
To get below about .25 or .23 the vehicle has to be designed around aerodynamics.

https://lightyear.one/news/

Latest entry is Sept 19.................still not seeing it...............oh, now I see it.

October 29, 2019
https://lightyear.one/news/a-car-bui...rgy-efficiency
Video in link above.

Still do not see where it a projected or test results number, but still watching the long video.

First you need to consider both Cd and frontal aera. I could make a jumbo jet with a low Cd but it would take an enormous amount of power because of the frontal aera.
Second, I don't think that classifies as a production car. The VW XL1 was actually in production even If not available in the USA. It was .189 Cd so it beats the Lightyear's goal.

Good points.

Looks like the earlier VW-L1 (Diesel - tandem seating) never made it into production.

Volkswagen 1-litre car
https://en.wikipedia.org/wiki/Volkswagen_1-litre_car

The XL1 was not a 5 seater.

Who said anything about 5 seaters only?

They produced 250 right? The price was better than the zero production vehicles so far by Lightyear.

https://www.greencarreports.com/news...erodynamic-car

The VW XL1 is no longer in production.

But the Lightyear isn't a current production car either. That being said, once one car sets a record it holds the record until being beaten. It doesn't lose the record just because it isn't currently being produced. I have a feeling VW (and other makers) may have a few other pre-production projects out there that also might be better as well, the difference is they aren't making promises looking for deposits. Build the car, deliver it to customers, then you can start claiming record this or record that.

PS I just re-read the quote. They said "Lightyear One will likely be the most aerodynamic car available in the market." Of course the VW XL1 is available on the market, just used (although the few that have shown up are actually still actually new with like 10 miles on the odometer). So they say "likely" and they actually mean "new market".

Does anyone know the frontal area of the XL1 or the Lightyear? CdA = Cd*A is more important than just Cd.

according to this the XL1 is 1.50m2 frontal aera (at 2:22). So smaller than a 1st gen Insight. Also according to ecomodder Wiki, the overall CdA is 3.00 compared to 2.98 for the Aptera. That's pretty good considering the XL1 was not just an idea of what could be.
https://www.youtube.com/watch?v=dF_GUFB5mfo

Lightyear has sold over 120 vehicles in pre-orders. Production has yet to start. Deliveries are expected in 2021.

What's your take on Lightyears focus on energy efficiency - and as a result of that increased range? Where do see the EV market developing? Which variables are you expecting to be important?

LightYear did, as Kach22i's post kindly shows.

Let's hope the LightYear One will sell in bigger numbers that the XL1 did.
At least they aspire to, something VW never did.

I somehow have the feeling that the need to have a large flat surface for the solar panels actually (slightly) increases the air resistance. The roof line follows the template, but the sides are almost straight.
If the cabin curves / tapers inward more back and forth the Cd might be even lower.

But that would leave a smaller, more complex curved surface for the solar cells.
The use case for the LightYear is focused on its ability to harvest sunlight, so I can see how ultimately maximal solar cell area takes prevalence over getting the last 0.01 Cd reduction (and that's assuming my feeling is correct in the first place!)

All in all, nice job. If I had loads of money I'd certainly be tempted.

If you need a bunch of qualifiers it's not "the most aerodynamic car". Especially considering it not only wont have the lowest CD but it will also have probably 1.5 times the frontal aera. Overall it won't be more aerodynamic than a Gen 1 Insight.

Not to sidetrack the thread, or dispute the math but those old black and white pre WWII films NACA did on bi-plane aircraft bracing planted a disturbing seed in my head.

If I recall correctly what they showed was a round guy wire in tension having similar drag to teardrop shaped wing bracing of ten times the guy wire size.

If my memory is not faulty, then shape is far more important than size which runs contrary to the math quoted above.

Turn down the sound - sorry, could not find the original narration.

1935 Aerodynamics Air Flow and Flow Separation NACA 1
https://www.youtube.com/watch?v=pb38NU-fKXw

EDIT-1:

Found this......................

Dramatic drag comparison
https://ecomodder.com/forum/showthre...son-32585.html
Sorry about the blurry image - freaking Photobucket.

Not 10X, but 35X ?

Still reading that old thread.

https://ecomodder.com/forum/showthre...n-32585-2.html
EDIT-2:

Here is the link to those old films - with original narration.

2013
NCFMF Video: How to Reduce Drag
https://ecomodder.com/forum/showthre...rag-25378.html

I see your point, it can be a bit misleading. However that is marketing, and if you are not promoting in your best interest then you are not doing your job.

The claims I find very interesting are the ones on full sized pick up trucks, their power, payload and towing capacity.

Each manufacture seems to have a niche at which they can claim top prize in their respective class.

Interesting, I didn't know it wasn't just a function of a straight multiplication of the size. There must be a precise formula based on wind tunnel results. It also may be completely dependent on speeds. What's good for a jet at 600 mph is not necessarily the best for a car at 60 mph. It's hard to argue with the 250 mpg results of the XL1. That just plain blows away any other production car ever.

Lightyear One windtunnel
 

I wonder what the battery level was before and after the 250 mpg run.

If the battery level is lower at the end than the beginning, then it gives a false impression of better MPG.

The XL1 is a PHEV..

250 MPG seems high; I would surmise closer to 125-175 mpg real world driving, and 200+ mpg only if used as a PHEV and the electricity cost is ignored. Or if you're a hypermiler.

"250mpg" is very much like how the Chevy Volt gets "106mpg" (e). As I understand it, once the XL1 is fully on diesel it's a still-impressive "up to 120mpg US" as per the very generous European cycle. Under this same testing regime the 3rd gen Prius is rated for around 60mpg, around 20% higher than EPA.

Had it been sold in the US you might expect the XL1 to get an EPA combined fuel economy rating right around 100mpg once it's not running on electricity.

This is the test you are referring
https://www.automobilemag.com/news/2014-volkswagen-xl1/
Still that's a big guy, running up apine mountains passing other cars and getting 160 mpg. It's only a 5.5 kw pack, but agreed just like any other hybrid it gets an artificial boost in ratings. Still 2.5 times better than a Volt which is excellent is outstanding.

Agreed. I'd love to own one. :D