At low speed the engine bucks and white smoke pours out of the exhaust.

What is your question?

My mech says he doesn't know what is causing it and that I need to take it to the dealership, which is quite a ways away. Any suggestions would be helpful. Car has 91k miles on it.

What makes this problem better or worse?

just happens at low speeds, when it makes it to upper gear it runs ok

How long has your 2008 Smart Fortwo had this problem?

just started two days ago