That depends on what you mean by a "free" market, which is even more complicated than the "free as in speech or free as in beer" of software. One meaning is as the opposite to a controlled market - one where participants and/or prices are regulated and you don't have a natural supply and demand. Obviously the car industry doesn't have that (but it did in the past, like the development of the Volkswagen in Germany), so in that sense it's free.
A second idea of a free market is a functional, competitive market where there are realistic choices and practically possibilities for new entrants to enter the market. The first definition doesn't exclude monopolies, oligarchies, collusion and cartels, dumping, price discrimination, exclusivity deals, IPR (imaginary property rights) lockout or any other number of anti-competitive behaviors.
A third idea of a free market is being as close as possible to perfect competition, a mostly unreachable ideal where you have cutthroat competition that'll constantly underbid each other until they sell at marginal cost and no profit is made. Lowering barriers to entry might be one way of trying to "lube" the market into functioning smoother, or you could for example require stores to show prices per kilo/liter to improve price transparency.