could one of these wires also be under the Dash of a 2014 Smart. When I installed my Underdash Subwoofer box I saw a very simular wire under there. At first I thought i may have disconected something but seing how it was taped off to hang there, I just left it and moved on. I have not put a speaker in the box yet. I originall had the stock radio over drawer am fm radio. I later installed a plug and play Smart High end am/fm dvd navagation unit. Now I will be wanting to add the subwoofer and really do not want an additional amp. If could hook into a pre existing rear or dash area speaker wire that might do the trick.I know this is an old post, but I thought I'd share the answer in case it might save someone else time in the future. The second set of speaker wires are likely near your seatbelt reels on either side.
Search for "From the end of 2010, smart were good enough to fit the wiring for rear speakers to most cars." on this page -> Evilution - Smart Car Encyclopaedia