Especially in the first few months babies should be transported in the car as little as possible and if only for short distances. On longer journeys you should take a break every 1 - 2 hours, take them out and move around. Babies should not remain in the same position for a long time as it may possibly influence the further development of their bone structure and muscles. We do not recommend driving in the car for hours or leaving them in the seat at home while sleeping. The little ones sleep, play and crawl best on the flat surface.
There are no fixed standards for this and ultimately it is an individual decision, which is partially dependent on the development of the child. If you have doubts please consult your pediatrician.