A SmelLorean is a smell that reminds you of someone or thing from a time before now, be it your childhood or an old relative. It is a transportational reminder through smell back in time. Play on words of the DeLorean time-machine from Back to the Future.
Alex was on his lunch break walking through the park. He walked past a car that smelled of a mixture of smoke and vanilla car-freshner. He was transported to a memory of an old girlfriend that he had at school whose car smelled just like this one. Alex just experienced a SmelLorean.