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?
Personally I am not telling God what to do when I pray. I am asking for his wisdom ,guidance and grace. I believe God is all powerful and he ask us to pray so why would I not do so. If he has asked for people to pray to him it only stands to reason that he listens and judges accordingly to the worthiness of your prayers.