A woman's body, especially when it is very appealing. ("Chassis" is a name for the frame of a vehicle.) OK, so she's not a great conversationalist, but look at that classy-chassis! She must work out.
classy-chassis(... ˈtʃæs i)
n. a really fine and stimulating woman’s body. (see also chassis.) She has one fine, classy-classis.