What Car? says...
When it comes to car names, especially those from German brands, it's usually safe to assume that the bigger the number, the bigger the car. Of course, there are always exceptions to any rule and the Audi Q8 is the perfect example. Eight might be the largest number in Audi’s model line-up, but this coupé-inspired SUV is actually a little shorter than the Q7 on which it’s based.
Combine this fact with the Q8’s less boxy silhouette, space is naturally a little tighter inside. That meant Audi couldn’t fit in a third row of seats, so there’s only room for five, including the driver.