I agree with the Viper having a low level of material quality. The SRT models are vastly superior to the early cars, but still not what most people expect in a near $100K car. That said it's mission is to be basic in all areas except speed. There are no American sports cars that come anywhere near Mercedes BMW or Audi interior materials or quality. I had to upgrade the inside the day I bought it! Picture below.
My comparison with the SLS was simply that for $200,000+ it should be quicker and better looking. I mean they put 600+ hp engines in a few other Mercedes models, and what's up with the power limiter in 1st and 2nd gears? To protect the transmission?

When they make a convertible SLS, I might change my mind, but it would need a complete rearend re-do.