Big boy bed and no more naps

Luke has graduated out of his crib and onto sleeping in a big boy bed. He learned how to get out of his crib and was starting to climb out a lot at night and it worried me that he would fall and hurt himself. Not only that, but Halle was ready to be in a crib and out of the pack n play she was sleeping in. I was really hesitant to move him out of the crib because I figured he would refuse to take a nap if he didn't have the obstacle of getting out of the crib in his way. But once he learned how to get out of the crib he started refusing to take a nap anyway. So on Monday we put his twin mattress on the floor to try out the big boy bed. I went and bought some Lightning McQueen sheets (from the movie "Cars" that he loves) to get him excited about his new big boy bed. He has been doing great in it and made the transition just fine. He rolls off the sides a lot at night so when I check on him throughout the night I always end up lifting him back into the bed, but he likes it and gave up the crib without a fuss at all. He is proud of his big boy bed and loves to show it to people who come over.
I'm afraid to say that the end of the crib may officially mean the end of regular naps for Luke (unless we get really lucky and he all the sudden decides he wants to do the nap thing again). The hard thing is that every afternoon he is tired and I can tell he needs a nap and if he doesn't get one come 6:00pm or so he is so tired that any little thing throws him into tantrum mode. So pretty much the only way I've been able to get him to nap is by taking him on a car ride and letting him nap while we are driving. So lately I have been planning my day around our nap-time car ride. So here he is snoozing away on our afternoon nap-drive.