I believe the first one is right because you are getting the car
tomorrow; therefore, you are still technically waiting to get the car.
Also I've been instructed to only use past perfect tense when two
things occured in the past and you want to let the audience know which
event happened first. (Does this sentence make sense??)
If you want to express that you are not waiting for the car anymore,
you could say "I had bought the car after I waited for so long." Does
this sentence work? It implies that first, you save money and wait,
then you buy the car.
Hope this helps (Please check that sentence, it felt funny when I wrote it)