At first I thought the OP's premise was complete bullshit and not even worth talking about, but the more I think about this topic the more it intrigues me.
A driving experience so boring that it literally causes you to be tired - There are many variables to that equation (road quality, weather, anticipation of eventual destination) but how large of a factor is the vehicle??
My question to the OP, do you think that if you were driving a more luxurious band like BMW or Mercedes that you would have been fully awake for the entire trip? If so, why would that be?
Is there some deep psychological zone that we allow ourselves to go to when we think "oh yay... Toyota." vs "Its if fking beamer dude!"
I think this thread could be linked with the "manual transmissions are obsolete" thread because it discussed pretty much the exact same thing : what makes a driving experience pleasurable/worthwhile/engaging.