I've always supported in spirit the BMW Art Car program, even though I hate some of them. So if an individual artist takes it upon himself to artify his own car, I can't criticise. Nothing a media blast and respray wouldn't fix. I agree with imp75, the brushstrokes detract here, but could be fixed with lots of sanding and some clearcoat. Though, sometimes brushstrokes do work, as in Esther Mahlangu's 525i, where it fits in with the African decorative craft motif.
I'm not a fan of Shephard's style, but on a car, it does sort of work, provided the brushstrokes are dealt with. As long it's not my car, I appreciate the artistic endeavour. Art does not require us to like it, but asks us to consider, comment, and criticise. Done.