I am very sceptical about that claim as it looks quite close to the current design which itself is a quite dated look IMHO but that is a different question. Not long ago, Mercedes made headlines claiming their CLA sported an industry best Cd of 0.22 and we all thought that that was indeed an achievement seeing as the other low drag designs at the time were all quite boring in comparison. MB maintained their claim for years until an independent organisation did measurements and discovered it was nowhere near 0.22 but by then no one was listening. I don't want to label everyone cheats without proof but I can tell you it's not an easy job reducing Cd and keeping decent proportions.
Yes, highly suspect.
There is nothing on this car that suggests it's anywhere close to .22. The only thing it's got going for it is the rounded "pointy" front. It's not wide and flat, but tapers from all angles to a "point". This is where Tesla is really shooting themselves in the foot. The nosecone was good, but flattening the front on the new models is raising the Cd. Fortunately, not by much because the part that first contacts the air is still relatively small in area. The teardrop is the most aerodynamic shape and a rounded Saleen-esque front fascia is the best design.
But, even then, that's only one piece of the puzzle. There's too much going on on the front and sides to promote smooth airflow. The windshield is too upright and juts backward too suddenly. That's going to launch air upward, creating a low pressure zone on the roof and all that air comes crashing down on top as turbulence. The trunk area slopes down too suddenly. There is a reason the Model S has an elevated trunkline compared to other sedans with a gentle slope to the spoiler. You want to guide air to the back as smoothly as possible and the 5-series is going to have another low pressure zone on top of the trunk adding turbulence to the turbulence.
Now, Tesla has another problem with the high trunk because air has to go behind the car and usually gets sucked right into the back, causing turbulence. if you can slope the rear of the car all the way to a point (again with the teardrop), you can eliminate low pressure zones and turbulence. This is why the "kammback" (seen in images above) is so great. It moves the car further toward the elusive teardrop shape for maximal aerodynamics. But this obviously looks ridiculous, so what's the next best option? Spoilers or spoiler shapes. These are great at mitigating this effect and that's why all Teslas have a "spoiler" built right into the body panels. This is extremely exaggerated on the 3 for maximum aerodynamics.
The 5-series has none of this. Additionally, the back of the 5-series has lots of stuff jutting out... taillights, trunk, crazy "sporty" lines, tailpipe (!). It is also angled straight down and is boxy. Tesla is smooth and sloping and the bottom sticks out a bit (back is angled) to alleviate the turbulence as much as possible. It's also round when looking at a top down view. This is still the worst part of the car, but is designed as best as possible while still looking good.
And another thing! Throw that antenna shark fin on the top and there's another aerodynamic problem. Not by much, but anytime you have a shape where air flows over or around and then suddenly there is no more shape, just empty space, that's turbulence city. You want air to hug the contours of shapes as much as possible.
This was fun! But there is no way in hell the BWM car revealed in that article has a .22 Cd. Also, this wasn't meant to be a lesson to you, I just happened to start typing and the keyboard got the best of me.