My DS sleeps for around 1 1/2 hours at lunch time. However, if we're in the car before his nap and he falls asleep, he will not go back to sleep when I get in and put him in the cot.
So today, we went swimming and then he fell asleep (despite my best efforts!) and slept for 6 minutes in the car (I timed him). I then put him in the cot and he was awake after 5 minutes and has been awake, but whinging in a tired way for 30 minutes. So an 11 minute nap instead of 90? I can't believe this is enough sleep!
Is the answer just to do everything to keep him awake in the car? Today I had the air con set to stun, radio on loud and kept tickling his feet but still he fell asleep. I think I would have to pull over and actually wake him.