OEMs and low-drag cars: What gives?

[Vman455]

After seeing the new Prius, I'm guessing--purely from the looks of it, so I could end up being pleasantly surprised--that there will be little improvement in its drag coefficient, if any, from the current Cd .25. The new Volt, in the same vein, claims Cd .285 versus the outgoing model's .28. Nissan claims the same for its Leaf, the first affordable electric car in production and one that, you would think, would prioritize low drag in the name of range extension, while its GT-R boasts Cd .26.

On the other hand, we have luxury manufacturers like Mercedes openly proclaiming that their cars will have drag coefficients closer to .20 than .30 by 2020, and their current S-class and C-class claim Cd .24, E-class .25, and CLA .22 in its lowest-drag configuration (sadly, not available in the heathen New World, but it exists and is feasible for mass production). The BMW 3-series is Cd .26 in its lowest-drag production configuration, while the i3 electric car balloons along with Cd .29.

These manufacturers are clearly capable of designing lower-drag cars that look "normal" enough for not just mainstream consumers, but luxury buyers to embrace, yet the models that supposedly prioritize efficiency as a guiding principle don't seem to be given the same aerodynamic attention as the more mainstream ones when this would seem to be a simple and cost-effective way of improving them that requires no technological break-throughs or mechanical development. Whether that's because of funding allocations, management structure, or some other reason, I find it fascinating and troubling at the same time.

[aerohead]

Originally Posted by Vman455

After seeing the new Prius, I'm guessing--purely from the looks of it, so I could end up being pleasantly surprised--that there will be little improvement in its drag coefficient, if any, from the current Cd .25. The new Volt, in the same vein, claims Cd .285 versus the outgoing model's .28. Nissan claims the same for its Leaf, the first affordable electric car in production and one that, you would think, would prioritize low drag in the name of range extension, while its GT-R boasts Cd .26.

On the other hand, we have luxury manufacturers like Mercedes openly proclaiming that their cars will have drag coefficients closer to .20 than .30 by 2020, and their current S-class and C-class claim Cd .24, E-class .25, and CLA .22 in its lowest-drag configuration (sadly, not available in the heathen New World, but it exists and is feasible for mass production). The BMW 3-series is Cd .26 in its lowest-drag production configuration, while the i3 electric car balloons along with Cd .29.

These manufacturers are clearly capable of designing lower-drag cars that look "normal" enough for not just mainstream consumers, but luxury buyers to embrace, yet the models that supposedly prioritize efficiency as a guiding principle don't seem to be given the same aerodynamic attention as the more mainstream ones when this would seem to be a simple and cost-effective way of improving them that requires no technological break-throughs or mechanical development. Whether that's because of funding allocations, management structure, or some other reason, I find it fascinating and troubling at the same time.

Hucho mentioned that aerodynamics has never been an issue of technological feasibility,but rather the priorities of the committees whom decide what will be built.
The aerodynamicist delivers the data to the committees, and has no say in what is done with it.

[UltArc]

Could there be an aspect we are missing? A variable unnoticed? For example, does the i8 need as low of a CD if the frontal area is much less? I am not saying THAT is the answer, rather saying I imagine there is another factor at work. Though, something comes to mind.

Is there room for a great CD? The Prius is a utility vehicle. If it compromises a feature (space, seating options, whatever), then the customer (as long as they aren't getting it to show the world how green they are) will just go to Ford or Honda. It has the ICE, the hybrid, and all the features needed all squeezed in.

Tesla skips the ICE, and is making a niche product- if you don't like it, pound sand. Mercedes are skipping the electric. Same, they make a luxury product. As long as they keep their style and don't let another big G manufacturer step in, no worries.

Koenigsegg (the pinnacle of automotive performance) and Lamborghini (the pinnacle of automotive performance for people who don't know about Koenigsegg or much about cars) both have said they aren't wasting their time on hybrids. It is too heavy, and takes up too much space for the performance gains. A different application, yes, but not having to work with the extra junk makes life easier. Just spitballing, really, but there may be something to it- compromise your cars purpose, compromise your CD?

[freebeard]

Could there be an aspect we are missing? A variable unnoticed?

'Poors' shouldn't get to have what the better people have.

[UltArc]

I Couldn't comment there...

...but I would argue that if a base model Mitsubishi Mirage had the same level of engineering as a Mercedes S Class, I don't think it would be the cheapest new car in the US.

[Vman455]

Originally Posted by UltArc

For example, does the i8 need as low of a CD if the frontal area is much less? I am not saying THAT is the answer, rather saying I imagine there is another factor at work.

Actually, the i8 is Cd .26.

The i3 is a bit narrower than a 3-series, but taller. CdA for the i3 works out to .69 m^2, but .64 m^2 for the 328i. The i3 with range extender is even worse, at .71 m^2 (presumably from cooling for the gas engine).

[oldtamiyaphile]

Originally Posted by UltArc

Koenigsegg (the pinnacle of automotive performance) and Lamborghini (the pinnacle of automotive performance for people who don't know about Koenigsegg or much about cars) both have said they aren't wasting their time on hybrids.

The Koenigsegg One is a hybrid. Supposedly the fastest production car in the world. Lamborghini will have to follow Ferrari, Porsche and McLaren into hybrids if they want to be faster than an electric sedan.

As far as aerodynamic drag goes, if you look at all the 'poor' aero cars, they all share a poor fineness ratio, they're tall boxy practical designs that will never match the sleeker shapes from Mercedes or Tesla.

There's also the payback to consider, just like going from 10mpg to 20 is a huge jump, while going from 50mpg to 60 isn't really a lot, going from 0.28 to 0.20 probably isn't worth the cost and (styling and practicality) compromise.

[UltArc]

Originally Posted by oldtamiyaphile

The Koenigsegg One is a hybrid. Supposedly the fastest production car in the world. Lamborghini will have to follow Ferrari, Porsche and McLaren into hybrids if they want to be faster than an electric sedan.

As far as aerodynamic drag goes, if you look at all the 'poor' aero cars, they all share a poor fineness ratio, they're tall boxy practical designs that will never match the sleeker shapes from Mercedes or Tesla.

There's also the payback to consider, just like going from 10mpg to 20 is a huge jump, while going from 50mpg to 60 isn't really a lot, going from 0.28 to 0.20 probably isn't worth the cost and (styling and practicality) compromise.

The One:1 is not a hybrid...do you mean the Regera?

"Given this, the Regera is not what we at Koenigsegg would call a hybrid, as it does not have the traditional shortcomings of a hybrid. Instead, the Regera is a new breed of Koenigsegg – and car for that matter.

Traditional, so called parallel, hybrids are compromised and heavy, as they have two independent propulsion systems. Alternatively, series hybrids are less compromised when it comes to weight, complexity and costs, but instead they are compromised when it comes to efficiency, as there is too much energy conversion going on.

This brings us to the Koenigsegg Direct Drive Transmission or KDD for short – invented by Christian von Koenigsegg and developed for the Regera by the Koenigsegg Advanced Engineering team.
The patent pending KDD system replaces the combustion engines traditional transmission and gives the added benefit of pure EV mode. What is unique is that the KDD manages to create direct drive to rear axle from the combustion engine without the need of multitude gears or other traditional types of variable transmissions, with inherently high energy losses."

This, and more found here: Regera - Koenigsegg | Koenigsegg

I absolutely agree on the fineness ratio, a major component. But I would not consider the Regera a hybrid, at least not in our common sense of the word. Lamborghini is [supposedly] working on a limited edition hybrid to put them in their place (paraphrasing) and show they can do it, but their focus remains advancing what already works more efficiently, or to move in the Koenigsegg path and find a system that does not have the drawbacks of a hybrid system.

[Vman455]

Fineness ratio--yes, that would be a big part of it. Those large luxury sedans tend to be very long, and that must make lower drag coefficients more easily achievable.

Despite what Koenigsegg says, the Regera is a hybrid--three electric motors, 2 driving the rear wheels and 1 on the crankshaft; electric-only propulsion up to 30mph and gas propulsion above that. Where it varies is in the true single-speed, non-variable transmission that directly couples the gas engine to the rear wheels at the final drive's 2.85:1 ratio. But, as Car & Driver notes, this system is almost identical to what Honda uses in the Accord hybrid.

Apparently, Lamborghini showed a car this week to owners, but we won't get to find out what it is until next year.

[Vekke]

New A4 is looking quite nice. 0.23. See how the mirrors are moved away from a pillar corners which is the rigth way to go .
Audi chooses high technology but cautious design evolution for new A4 - SAE International