How can i model this part of the car with good topology?
Ok I experimented a bit, and got this. But how can I make the little square sharper? Creasing doesn’t work. And by adding new loops, I just would mess up the topology. What do you think?
Select square loop and extrude, perhaps?
No that wouldn’t work ): . I think there is no other way, than adding more edge loops, so I made this.
It looks like you are trying to get the little turn signal indicator modeled properly. Personally I would model it separately and join it to your body.
I agree with place57 , sometimes its just better to model bits separately than trying to keep everything in one mesh. After all the end result wont show the bit under the signal indicator. Things like that have puzzled me for my bus modelling, but now I know I am building smaller details as separate items. Gives you better cars body topology too 
Ok thanks for your help. Maybe I really should model this part separately :yes:. But I will have to restart modelling anyway, because it is better to start low poly, and then add the details in the end.