The working relationship between the three lead main characters is a bit contrived, especially in the early episodes. I honestly found it hard to believe that they would stick together long enough to eventually race together. I also found the tech savant to be difficult to warm up to, but this is balanced by how likeable the samurai character was.
With the short run time, the biggest problem was the villian. They only start antagonizing the cast directly in the last four episodes, and their scheming is slightly orthogonal to the thrust of the cross country car race. This means that that they felt more like a random obstacle rather than something that would bring the story together at a climax.
The biggest strength of Appare-Ranman is the strong supporting cast of characters (these characters wear flamboyant outfits that run the gamut from "cool" to "what?" to "oh no"). Each of the racers is decently well developed given the constraints of a single cour series. They played off of each other surprisingly well and helped invigorate the proportionally high number of breather episodes.
Animation and production values are extremely appealing. There was clearly a decent budget here.
