Not to sound like the biggest jerk, but I suggest you type mobile cart (and things like it) into the search feature on this site (or into a search engine) and uncover a plethora of very recent threads on the subject.
Really and truly not trying to put you off of the folks here at bX or anything, it's just been brought up a ton lately, that's all.
oh... and since no details regarding budget, market, needs, requirements, space, plumbing etc were brought up... I'd say rock a Speedster :)
My own experience has shown me that the:
1. Cart itself is the marketing device and strategy. Have a Cart that is attractive to the general public.
2. People also love clean along with cute.
3. My selective market and success (believe it or not...) is not in the morning. My sales days begin afternoon and go until about 6 to 7PM.
4. Go to were the people are walking or sightseeing in their cars. Go to were you will be noticed by the public, but NOT upsetting to merchants. Merchants are your biggest caution flag.
5. Do not be perceived as a threat by other businesses or civic minded people, but be perceived as an attraction to the community.
6. The two biggest comments I get are, "Oh, how cute! and Oh, what a great idea"!
7. I COULD deliver to office buildings etc and that is an entire open market. Since I live in Monterey Ca. the beaches and wharf areas are the traffic draw...so that's where I built my business.
8. There are also events, car shows, air shows, motorcycle clubs, charity events, and private parties.
9. Be Mobile and have a trailer to trailer your cart to events if you will be full time.
10. Meet and have all the Health Department and city permits in order. Good luck.