Read the blogs and well, whatever car the chassis was based off of, it is now 2" longer to make room for the batteries. I also read that the chassis runners were changed from a continuous beam bent to the correct dimensions (lotus) to actually cutting and bracketing the runners in the correct shape (tesla design). Ease of manufacturing decreases the cost and the supposed 2" door lowering improves getting and out of the car, but it also puts more potential failure points into the design, ableit the points wouldn't be a high risk failure point. It does increase mass and the frequency modes of the chassis could change dramatically with this design change (aka changing the chassis stiffness). I wonder how much money this really saves in manufacturing the car. beam bending has been around for a looong time. Really, I dont mind the difficult egress in my current cars and im 6'3". If it affects the handling to drop doors 2" then im against doing this.
I agree with tony on the fact that manufacturers should start using higher tech materials. I believe most manufacturers agree with this too, they are just taking their time to adopt it. Now, major manufacturers use lightweight materials on low risk parts such as aero parts, roofing, mirror housings, interior pnls, and i believe as the risk to using the lightweight materials decreases, they will start tooling up more parts. They dont want to buy lots of material/tooling/training only to find out that when you stress it in 3 degrees of freedom at a certain rare frequency while its raining out, it destroys itself. That, and the fact that taking longer mitigates the risk and conditions the customer to the slightly higher prices. Nobody wants to buy a 3 series that one year is 50k and the next its 65k. but if its 50k, then 53k, then 57k then 60k...(increasing faster than inflation) people might take better to that thinking that inflation is the cause. meanwhile spreading the adoption costs (tooling/training/procurement) over multiple model years.
The tesla does have carbon fiber body panels.