Frontline spray will only kill where you spray, I think. Ticks like cracks, etc. Miss the cracks....

Ticks and tick nymphs have survived an hour of high heat in a clothes dryer. One site says that tumbler-style clothes dryers can reach 345F/175C (http://answers.google.com/answers/threadview?id=729373)
Previous posts here have indicated that interiors of black cars in AZ (I think) were only 130-140F (IIRC).

Personally, I would use the bomb. I would suspect that the possible danger from the ticks is worse than from the bomb. I would buy one from the vet. A lot of the topical flea stuff that they sell has been tested better than those sold over the counter, although I don't know if the same holds true with the bombs. Ask your vet.

Just use the bomb as directed, then open all the windows and let it air out for a couple of hours. If you have a garage, leave all the windows open for a few days. To be safer, use the "old" car for the baby for a week or so.

Or ask your pediatrician.

Sue