At first glance, you could easily be forgiven for thinking that Pacar is just a crap, lazy rip-off of Pac-Man, but with cars (the name is probably as close to "Pac-Car" as Sega could get without being sued). In reality, it's a pretty great rip-off of Pac-Man!
The fact that the ghosts and... yellow thing have been replaced by cars isn't just an aesthetic change, it leads to the first, and probably most important difference between Pacar and Pac-Man: cars go much slower in reverse. This means that if you want to change direction quickly, you have to turn 90 degrees. You can drive backwards, but it's a lot slower than going forwards, which is pretty dangerous when there are enemies around.
There are other differences, too. For example, there are two mazes instead of one. The game alternates between the two, and each time you clear both mazes, the end of level bonus increases, as does the number of blue cars in the maze.
Blue cars are the most common enemy type in the game, and they just passively drive around the mazes, not making any special effort to try and kill you. Each maze also has one orange car, that appears after you've been in the stage for a certain amount of time. The orange car is much more agressive than the blue ones, actively chasing you around and trying to kill you.
Like Pac-Man, Pacar has special larger dots that temporarily give you the ability to kill the enemies. Like everything else that Pacar takes from it's predecessor however, there's a little more strategy to the power dots.
Firstly, they aren't waiting ready on the map for you to collect them from the start, one appears for every 30 normal dots that you collect. Secondly, the blue cars can collect them, although doing so gives them no special advantage, it does rob you of the chance to get some extra points, both by killing the enemies (the points awarded for which double in the exact same manner as, that's right, Pac-Man), as well as the quite hefty 300 points that each power dot is worth.
There is quite a bit more strategy to the game that i won't go into here, since this is meant to be a review, not a guide.
In summary, though it's not quite as good as later maze games such as Raimais or Pac-Man: Championship Edition, Pacar is still a very good game, definately better than it's inspiration, as well as being a lot more playable today than a lot of it's contempories.