Custom car seats are seating choices tailored to the customer, made from components chosen by the individual to meet their preferences. A custom car seat has features not found in standard interior setups for most vehicles. Custom seating also tends to be more expensive than standard arrangements.
Car seats are meant to keep drivers and passengers comfortable throughout the trip, with standard models meeting a bare minimum of comfort with cheap materials. Custom seats have much-nicer materials, and mechanical features that might need to be adjusted to the size and shape of the vehicle's interior. Some companies offer special deals on their own custom seating setups, with personalized choices costing more.