I bought a used 2015 smart with 6k miles that the guy just drove as an advertisement for his business to trade shows. He had lost the 2nd key and the manuals, i went to a local locksmith like one group member suggested. It is really an involved processing to recreate the key since he used a Mercedes Benz online program. He had a programming box he plugged in and had to reprogram both keys at the same time (you can have more then two, but all keys have to be be reprogrammed at the same time, otherwise any key not reprogrammed wont work anymore. It was about $250-$275 For one key. The check engine light came on when I was driving home, so I turned around and drove back and by the time I had gotten their it had gone off. Love the car but everything costs. The 2015 replacement manuals cost $250 on eBay.