Anime

It’s easier to chalk it up to cars are like mecha- if they aren’t the focal point of the anime, producers are not going to find specialists, so you end up with CG cars and maybe that will be better than okay if the anime is mostly CG (for instance, you probably wouldn’t notice cars being particularly noticeable in Dorohedero).

To some extent if you watch enough anime, you will tend to notice issues with characters playing musical instruments if you play that instrument or with sports techniques when those activities are not the focus of the anime.

Cooking can look terrible when it’s done as a kind of afterthought, which is especially funny because most people are familiar with what food ought to look like. Cars are probably more important to Americans than cooking is, so the cars thing probably is more of an afterthought to anime production in general.

Because cars are quite complex and they move around they are time consuming and expensive to animate. Especially if a car turns and rotates relative to the camera, that is quite the job. They also are an object with familiar geometry so it needs to look correct and consistent, unlike character heads and faces for which we accept a lot of artistic liberty to be taken.

It comes down to some options:

• draw it well (takes a lot of resources)
• CGI but integrated very well by tracing over it by hand (also expensive)
• draw it using reasonable resources (probably won't turn out very well)
• CGI but don't redraw each frame (CGI will jump out as being CGI)

I remember the first episode of Non Non Biyori. Beautiful intro, one of my favorite introduction moments. The only thing that takes me out of it a bit are those ugly ass CGI cars lol. They really stand out!

For an example of good car animation? I don't watch much things with cars in it but in Lucky Star episode 6 it starts off well. They are either drawn or CGI that is traced over. When the initial D parody starts, the outside of it is clearly CGI, but the inside is drawn/traced. When you see the camera panning around the car, you can see that it would take a lot of time to trace each frame to make it blend into the art style and background. Maybe the CGI look has to do with the anime they are referencing, I didn't watch it.

In addition to what everyone else has already said: because unless you're making an Initial D sequel, the cars are usually not all that important. Studios want to save their budget for the important stuff, so they aim for "barely adequate" on the cars and move on. (Honestly? I notice the horses more.)

Initial D?

Because anime is designed to be quick, cheap animation. Lots of movement is slow and expensive. Especially moving towards or away from the viewpoint.