An alternative would be to simply sell a car with or without heated seats, at two different prices. This is how it was done. The subscription model gives the customer more flexibility, since if she changes her mind about wanting heated seats halfway through ownership, she can cancel and won't have to pay the full price of the heated seats option. Or vice versa - if she decides she wants heated seats, she can turn them on more easily with a subscription than going somewhere and getting them aftermarket installed.