Yeah they won't be able to compete against Tesla on aero, since Porsche said they want the Mission E to be able to pull off respectable lap times on the Nurburgring.

Which really smells like a lame excuse to me.

The much more likely technological explanation is that the Mission E cannot out-accelerate the Model S, because it cannot draw as much current (doesn't have as many high performance cells, doesn't have as good cell chemistry, etc.) as Tesla.

I'm pretty sure that if Porsche was able to beat Tesla in 0-150kmh acceleration then they would do so, because that's the speeds at which most customers of luxury/performance cars spend 99% of their driving time.

But they cannot: hence they are making up excuses, instead of admitting that Tesla has the better battery technology.