Did you miss my point that the dimensions are extremely close, so I figured I would be able to compare the two pretty easily?

I just looked it up and the A3 is very close to the same size as my older IS 350 and that thing is CRAMPED in the backseat. People 5’4” and under can do “fine”. 5’5”-5’10” definitely fit back there but it’s not comfortable. 5’11”+ are hitting their head and cocking their legs at an angle. And all of this gets even worse if the front row passengers are tall.