First of all, it isn’t really a candle, it is just an air freshner and no, it doesn’t plug-in!
Car Candles are $3 and depending on the climate you are in can last from a few weeks to a few months.
One trick that I use though is to buy the car candle and also buy the room spray in the same scent. Once I can’t smell the car candle’s scent anymore, I just give it a spray of room spray and wa-la!! it smells again!