I reported a problem about the engine missing then running normal in another thread, here . . . Engine service light went on then off
The fault codes were PO300, PO303 at 250 miles. Smart USA recommended changing the spark plugs and regapping to 1.0mm, which was done.
The same problem has happened at 330 miles. The Smart Tech says that Smart USA will now recommend replacing the injectors. He also said this is happening to other Smarts, specifically to some "Test" Smarts in Michigan. The injectors were replaced on the Michigan Smarts and they have run OK for hundreds of miles since the replacement.
The tech also thinks that warmer climates (California) and rushed testing may be part of the problem.
I'll report back with the results.