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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.

I'd trade them all for ventilated seats.

@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.

@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.

@Alex K

Any idea where Jurassic got its numbers?

@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 (

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

@Alex K

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

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.

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.

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.

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

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.

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.

VW XL1 = Honda Insight + 20 years.

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

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.

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

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.

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).

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!

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