If you really think about it, you are being a total douche when you pray for anything
You are basically telling god... that you know what is best, more than god does
By praying, you are saying...
"Hey god, I know you don't want to give me a new car, but I want it anyway"
"Screw your perfect/divine plan god, I want a new car... me me me me me me, it's all about me"
If it is god's will... why are you trying to change god's will?
Do you really think you know better than god does?
Or, are people just selfish and don't care what god has planned?
Praying is not just for saying what you want it is also for those that want to share their problems with too God. I think it is not being douce sayong what you want but entrusting that God would always be in control and His will be done. There is nothing wrong in sayig that you would like this and this but in the end, you know that His will be done and that is everything that you can hope for.