Before a pixel-perfect port was created for the Sega Saturn, the most powerful system to see OutRun was the Sega Genesis, and the least powerful was the Commodore 64. Comparing these two directly may seem unfair, especially to the Commodore, but actually this comparison is an interesting study of what makes an arcade port good.
When playing the Commodore 64 version for the first time, what is missing is more obvious that what isn't. Players must select their intended goal ahead of time, so there are no forks in the road. The tunes "Splash Wave" and "Magical Sound Shower" are available, but "Passing Breeze" has been cut. The road is always the same color as the rest of the landscape. Road-side scenery is best described as "minimal." And other vehicles apparently travel in swarms, because at any given time, all on-screen cars are exactly the same make.
Despite its shortcomings, however, Commodore 64 OutRun delivers where it counts. The graphics move fast, and are surprisingly smooth despite the largely "character-based" animation techniques used. Enough game play elements have been preserved to help fans see the racing game they fell in love with at the arcade. Sharp curves, rolling hills, annoying drivers, dangerous road-side obstacles, the always-ticking clock looming over everything... they may not look all that pretty, but they still make for an excellent adaptation.
Oppositely, on the Sega Genesis, it is easier to see what is actually present, at first. Screenshots show off the game's almost arcade-perfect graphics, while the console's sound system promises the most faithful playback of the original music. After a few plays, however, something seems missing. The music is certainly close, closer than on the Commodore, but, it isn't quite there. The graphics again are nicely detailed, but the hardware's lack of smooth scaling is a liability, making for jittery game play that chips away from any sense of real speed. Then there are little things, like vehicles that pass through each other, or the car that seems to flip in place following a crash, that further pulls the quality down. To be sure, the Genesis version does offer everything the Commodore version has and more, but even so, the presentation seems a lot sloppier.
Perhaps these ports are examples of the "uncanny valley," where the closer something is to the original, the more the differences stand out. Or maybe they're just examples of what can happen when more care and effort are put into the "weaker" system. That may not be exactly what happened here, but it sure seems like it.