Nice cases. Take it from me, you're gonna want to stop using their logo or they are going to sniff you out and shut you down for trademark infringement. It's not a question of if but when. As an artist I have a lot of experience with this as well. The car images are fine but you can't use their logo ar any of the car logos. That includes the word "Ferrari" in their trademark font. Not trying to rain on your parade, just trying to save you some aggravation before it's too late.
I contacted a couple of manufactures, (Ferrari is yet to reply) but the main response back was I couldn't use the logo in any fashion by itself. If the logo is on the car in a normal fashion such as how I get them from a customers photos it's fine to draw. I didn't think about the font though, thank you for the info. I'll be changing that on future pieces.
