Buying advice Smart for daily 100km

Hello, play with the thought of buying a smart. Aspiration is: Automatic or partial automatic air conditioning cheap in consumption/tax/insurance would need this weekday for 100 km per day. Grade in the small car sector automatic is very rare to find. That’s why I came to a smart. At the moment I drive a BMW F11 (yes, the switch to a smart is then quite big…) but this would get the woman since this has daily not such a long distance. I don’t want to scrub on the F11 every day these miles on it. Or does someone have another alternative where I could take a look. If Smart I would like the convertible. Which miles would still be reasonable with this daily load?