On 12/30 I received the same call, but was leaving on vacation on the next day. I returned Monday and set up an appointment for Good Friday.
I talked to sales rep who said it was for an "under-seat cable inspection". If you read some of the other posts here you'll see that it probably has to do with some of the transmission issues that have been going on.
These are cars with major redesigns and they will have bugs. I have spent my career in engineering and manufacturing for over 40 years and that happens with new products, even if MB is involved. I bought my smart for the future and I am not shocked or bothered by that. However, it is tough to waste a day to drive to the dealer to get repaired and I wonder if the "extended warranty" will nickle and dime me for factory bugs in the future, but only time will tell. I know there will be more dealers opening and closer so one part of my concern will be answered. I know that as the rest of you put miles on your cars that the bugs I need to be fixed will be found and addressed. Remember, this isn't "your father's Buick" that just got a new chrome hubcap to make next years model. It is a sophisticated, mechanical device that needs field use to find the issues.
There has been nothing in the automotive field that has been introduced, marketed and distributed like the smart car to date. The INTERNET had changed the face of the world and now the auto industry. Look at what this could do for auto manufactures to cut their costs of sales and distribution.....they are watching this car, this strategy and these postings. Keep the information flowing and keep it factual. And get your smart car in for inspection if you are called.