Coming to the point .... If a new car is equipped with leather poshish on seats ,than the fragrance will be there in car life time !
Normal vehicles when comes new ,got all new rubber parts and and seat covers ,which togethor makes a fragnance which feel pleasent to nose .... And after the time passes ,It vanishes !
So there is no such polish or spray whioch actually gives yo uthe brand new fragnance inside the cabin ,Though many products are available there in market which got even more better fragnace from the stock ! 