Combining Uber with Car Sales?

I work for a car dealership and have been taking lunch when I get a ping for Uber. It's nice making extra money on my lunch break but I've got an idea to market myself and make money at the same time. I can get some marketing materials such as car door magnets and/or window stickers (need advice) and that way while I'm driving for Uber I'm making money, and advertising myself. The idea is that while I'm not actively helping a customer or making phone calls, I can be driving. If they're interested in talking to me about what I do (since I drive in my work attire with my name tag), I can pitch myself to them and see if the rider is in fact looking for a car. We don't have a great amount of foot traffic for 12 sales people, but I've only been here for 2 months after 6 months at another dealership. Since I was recruited to work here do you think my manager will be okay with me leaving at different parts of the day to drive if I am marketing myself and possibly pitching to customers? Is this a good idea or does it sound stupid? I work hard but only had 10 sales last month.