"You can’t stand up in a Cadillac, either"

In this quote, Bill Lear is utilizing a metaphor to communicate the concept that often, even the most elegant and relatively best things have their limitations. Much like how one can not physically stand up in a Cadillac due to its low ceiling, there are specific restrictions and limits in life that can not be overlooked or overcome. This could be a tip to not get too caught up in material possessions or to not let our desires blind us from the truth of our restrictions. It likewise acts as a suggestion to value what we have, instead of constantly pursuing more.