Industry-leading drag coefficient boast...well, it was good while it lasted.

Industry-leading drag coefficient boast...well, it was good while it lasted.

Apparently the new 2014 MB CLA250 has a drag coefficient of .23

(and a hell of a nice looking car for under 30k to boot!)

Comes out in Sept., so I guess we have another 8 months or so of leading the field in that department left.

dahtye | 30. januar 2013

I don't like anything with tailpipes....
I'll take the Model S anyday over this car.

Kleist | 30. januar 2013

Great challenge to make the X 0.22 and Gen3 even lower. Elon will love this... Just the kind of engineering he wants from his guys.

Electron | 30. januar 2013

Soooo many buttons.....

rd2 | 30. januar 2013

I know. The buttons were actually nauseating to me. Amazing how quickly my tastes have changed.

Also, is that a trunk or a glove box in back? ;)

appljd | 30. januar 2013

Still has handles :-)

schumonster | 30. januar 2013


The driver's side window and mirror controls look familiar though...

nickjhowe | 30. januar 2013

ugly outside, fugly inside.

Tiebreaker | 30. januar 2013

Is that a Dodge Charger front?

Tâm | 30. januar 2013

I hate analog speedometer.

Scattered, unorganized center console.

Hey! It has Model S windows and side mirrors controls!

aaronw2 | 30. januar 2013

I think the LCD display looks tacky, like it's an add-on or something, not like something integrated into the vehicle. And I agree, too many buttons. The dash looks cluttered.

archibaldcrane | 30. januar 2013

Jesus, it's like a piranha tank in here!

DTsea | 30. januar 2013

Cd is the ratio of apparent frontal area to actual frontal area. So the Tesla has air drag equivalent to flat plate with 24% of the actual frontal area of the car.

The Model S is a lot bigger car than the MB shown and wetted area is part of drag. If the MB were as big (long) as the Tesla it would have a higher Cd, I believe.

pvenkate | 30. januar 2013

Does it say under $30K? I looked up in MB site as well. No mention of price..

archibaldcrane | 30. januar 2013

DTsea - that's interesting to know.

pvenkate -

"Pricing will range between $29,999 and $35,000 so as not to cannibalize sales of the $35,350 C-Class."

Robert22 | 30. januar 2013

After owning a 2000 S-class for over 12 years, I can say from personal experience that any claim made by Mercedes should be closely scrutinized. Information provided to me on multiple occasions had a "high fiction content" to quote a CEO familiar to us all.

Timo | 30. januar 2013

@DTsea, a bit wrong explanation, CdA is a drag coefficient with a frontal area in the calc, Cd is the modifier to that. The lower the Cd the better.

Does anybody know for a fact what the Model S Cd is? 0.24 is commonly accepted number, but AFAIK that is just estimation.

Kleist | 30. januar 2013

Drag coefficient is a claimed number, but nobody really confirms it. Check out the wiki list, EV1 is still #1 with claimed 0.195.

Kleist | 30. januar 2013

In case you follow F1 - windtunnels are notoriously blamed for not being calibrated properly. Mercedes didn't do well in F1 the last 3 years... maybe due to their windtunnel.

Timo | 30. januar 2013

Wind tunnel test could confirm it. Measure drag and add the frontal area = CdA.

Alex K | 30. januar 2013

@Timo | JANUARY 30, 2013: Measure drag and add the frontal area = CdA

In case anyone is interested, I measured the frontal area using the Tesla S web image ( and calibrated the pixels to meters using a neat free program called ImageJ ( The resulting area is 2.676m**2. CdA is therefore 0.24*2.676=0.64224. This can be used in Web programs, such as GreenRace ( to update the SCx value for the Model S.

If you want to recalculate the frontal area, use the following sequence in ImageJ:
Analyze->Set Scale... Distance in pixels:245, Known Distance: 2.18948, Unit of length: m
Analyze->Analyze Particles... Show: Outlines, Display Results
(Results Window displays area 2.676m**2 and an outline of the shape is also produced for verification)

Mark K | 30. januar 2013

I've owned a dozen MB's, and have a recent SL (a great car). My take on the CLA?

A fatty with a face lift.

Granted, a different market segment, but compared to the Model S, this future MB already looks old.

MB needs some fresh blood in design and engineering.

There are some grateful guys in California who'd be happy to help.

DTsea | 31. januar 2013

Timo, drag=(.5)*(air density)*(velocity squared)* Cd

The flat plate metaphor is an explanation for the layman, true, but since the true flat plate drag is irrelevant, it is explanatory. Calculated drag includes (for low Mach number) form drag, skin friction drag (wetted area and surface property driven) and excrescence drag (door handles and other protuberances). In practice computational fluid dynamics give good estimates for form drag, but total drag is usually determined from the wind tunnel and (for cars) the Cd is back-calculated from drag.

But that's all kind of a lot of explaining so I just shared the flat plate metaphor.

So said professor Harris back in undergraduate aerodynamics class. I hope I understood it right when I was grading all the juniors' aero homework when I was a grad student.


kkiri7 | 31. januar 2013


Nice to see a fellow aerodynamicist on the forum.
@Alex K, and @Timo, are you also in this field?

Good analysis.

Back to the topic: I just visited the link for the CLA250.
From a cursory look at even the front end, @Robert22 may have a point.

Regarding looks, without actually seeing it 'in the flesh', the 250 has a decent looking body. The Audi A7, though, looks much prettier, but our Tesla S still leads the pack.

As for the original concern, when the smaller Gen III comes out, as has already been explained, it should be easier to lower the drag for a smaller car.
Fortunately, the S has so many positives, only one of which is the drag crown.

- best.

kkiri7 | 31. januar 2013

P.S. The 'drag crown' I mentioned was for a King, not a ...

- best.

DouglasR | 31. januar 2013

@Alex K

When you plug in your numbers to the jurassictest site, does it increase or decrease the Model S range? By how much? Do you think your estimate is better than the one on the site?

TS | 31. januar 2013

"Mercedes will also offer a raft of performance technology such as its Collision Prevention Assist, which works at speeds above 4 mph. This radar-based braking system can warn drivers of a pending accident and pre-charge the brakes to create faster braking abilities. The CLA-Class lineup will also offer Distronic cruise control, lane keep assist, and blind spot detection system as part of a Driver Assistance package. "

TM, please make this as options soon ..
Almost every other premium sedan have simular options..

GLO | 31. januar 2013

Sadly it's a fossil fuel car...

jkirkebo | 31. januar 2013

Nice of them to put all the crap in the same package so it is easy to avoid it :)

Tylyoung | 31. januar 2013

Tesla, Nissan, even Ford are moving us into the future. I get excited reading about, driving a Tesla. Gas cars are, not yesterday but, just not where I want to go. The Tesla Model S is paradyme shifting, bringing on the future....soooo awesome!!

DTsea | 31. januar 2013

Tesla has all that. It's called 'human eyeball and brain.'

I personally would not pay extra for all the 'safety' things. My wife would. Each to their own I guess.

archibaldcrane | 31. januar 2013

I'd trade them all for ventilated seats.

Alex K | 31. januar 2013

@DouglasR | JANUARY 31, 2013: When you plug in your numbers to the jurassictest site, does it increase or decrease the Model S range? By how much? Do you think your estimate is better than the one on the site?

It decreases the range. Jurasic has SCx as 0.5. When using 0.64, a sample 115mi trip from Tucson, AZ to Phoenix, AZ going at 75mph went from 51.7% battery remaining to 44%. I can't say if my estimate is better, but it's more conservative. I would have to "calibrate" the numbers by actually going on a known route and seeing what the actual power usage is.

Alex K | 31. januar 2013

@kkiri7 | JANUARY 31, 2013: @DTsea,Nice to see a fellow aerodynamicist on the forum. @Alex K, and @Timo, are you also in this field?

Sorry, not me. Just didn't have anything better to do at the time.

DouglasR | 31. januar 2013

@Alex K

Any idea where Jurassic got its numbers?

Alex K | 31. januar 2013

@DouglasR | JANUARY 31, 2013: Any idea where Jurassic got its numbers?

No idea. They haven't updated their web app in a long time and some of their numbers (weight of car) are not correct. It's always a pain when restarting the web app to go in and change all the numbers to correct values. I am tempted to spend some time and rewrite the app and make it pure Javascript rather than Flash based. The hardest part is getting the elevation information for a given route and that is actually quite easy as Google has an API for that and a sample app (

Timo | 31. januar 2013

@kkiri7, same as Alex K, I just had too much time in my hands.

DouglasR | 31. januar 2013

@Alex K

If you rewrite that app, I'll buy it. particularly if you can add in a parameter for outside temperature (see :)

Cattledog | 01. februar 2013

There was a moment a year or two ago where they reported a Cd of .225, but I guess final production was a bit more turbulent.

Brian H | 01. februar 2013

I think they might have been hoping to get away with the camera side mirror replacement they showed in the X. Or maybe they were counting the now-cancelled aero wheels.

Oliver in Seattle | 22. februar 2013

It gets better. VW jut green lighted the XL1, a two seater that uses less than 1 liter to go 100Km (it gets 261 mpg). It's a 2cyl diesel hybrid. Drag coeffecient of 0.189. Made or carbon reinforced plastic. Very cool.

Oliver in Seattle | 22. februar 2013

That should be 'just green lighted'
Here's the link

Kleist | 22. februar 2013

the relevant number in the report is 160 Wh / mile ( 0.1 kWh / km ). Model S is about 320 Wh / mile. So there is room for improvement.

Brian H | 23. februar 2013

That's a tiny 2-seater; no comparison. Quantity? Price?
But VW certainly pulled out all the tech stops! Used its deep pockets and resources to the full.

Cattledog | 23. februar 2013

VW XL1 = Honda Insight + 20 years.

Timo | 23. februar 2013

More like VW XL1 = GM EV1 +20 years. Look at it, it looks almost exactly like EV1.

Timo | 23. februar 2013

No comparison in efficiency either, Model S is big five-seater car which means a lot bigger air drag even if it had same Cd, it is heavier, using materials people are actually able to purchase and it get five star safety rating, which I don't believe that VW does.

Brian H | 23. februar 2013

How many will be made and sold, for how much $$? Is this pricey vapourware?

olanmills | 23. februar 2013

Well it's cool that they got a great cd, but I don't really think Mercedes look very good on the outside, even this one. The inside is just plain ugly.

Kleist | 23. februar 2013

I wouldn't dismiss it... you can always learn from your competition. This will be - if at all - a hand build technology demonstration, like the Roadster was. Given its size the MS is the most efficient EV on the road today, but this shows us a little the path to Gen3. Good ideas you take and make your own, for the expensive stuff you find a more cost efficient alternatives. Gen3 large option: 240 W/m with 60 kWh battery gives you 260 m EPA - perfect for the then deployed super charging network (MS owners already paid for it).

Thumper | 23. februar 2013

The MB is a pleasant looking car. I am skeptical of it being slipperier than the MS. Does it have a full belly pan, or is it a tangle of pipes and plumbing? Whatever the cd numbers, if both are put in the same wind tunnel at the same time, I'm betting on the MS!