Super cute. I love your style. It's got just the right amount of underground comics style. Since it's concept art, I figure this was simply of little importance, but the background is definitely lacking compared to the foreground characters. It's a bit jarring to have these super edgy looking characters and vehicle design against obviously digital work.
Love, love, LOVE the vehicle design and I'm very curious to see what you do with the characters. I've added some of your pages to my webcomics folder.