L.
Hi!
I have an 8 month old son that sounds exactly like yours. He was like this at 6 months old. I decided to do the cry it out method "my way" and it worked! It worked by me being home at the SAME naptimes everyday and not letting him fall asleep in the car or stroller. If he does that for even 5 or 10 minutes it ruins it for the day and I don't even make him try. At the same time everyday(3 hours after he wakes up and 3 hours after his AM nap is over) I put him in his crib. The first few days were torture--one day he cried for 45 minutes! Every 10 minutes I lay him back down, put on his mobile, and do NOT talk to him. This went on with varied amounts of crying for a few days. Now I have NO problems. He might whimper a few minutes or play quietly in there for a little bit, but he goes to sleep. He usually sleeps 10 hours at night(8PM-6:30AM when I wake him) and 1.5-2.5 hours each nap. He is a much happier baby with a regular nap routine(and I am a happier mom) and he now rarely falls asleep in the car!
Good Luck!