The list is amazingly odd. I get that a BMW 3 series is acceptable but an M3 is not -- perhaps they don't want customers being given rides by those who fancy themselves "performance drivers".

But the Subaru Impreza WRX but not the Subaru WRX? They're the same car! Impreza not acceptable, but WRX is? That turns the "performance vehicle" thing on it's head.

Many small luxury vehicles (Audi A3, etc) are not acceptable. Okay, fine. But the Prius is! But the Lexus Ct200h (which is a Prius with a fancier badge) is not acceptable.

The BMW 3 series is acceptable, as is the 4 series coupe, but the 4 series Gran Coupe (a Sedan version of the 4 series coupe, which is a coupe version of the 3 series sedan.. yeah, don't ask) is NOT acceptable?

Passenger can see the vehicle when choosing a ride in Sidecar. What the original comment was implying is that Sidecar is less picky on its vehicle requirements.