Originally posted by Fujiwara Takumi
*ahem* sorry to paraphrase, but: "you have worked for me for many years, this car is part yours."
Okay, sorry. Since most of the money was used to fix the car belonged to Takumi, the car is "partly" his. Takumi does not own the car entirely. At least this is by going with the anime.
I think that the car was given to him entirely in the manga so that he has means of transportation while Bunta still worked at the Tofu shop and got himself a WRX...