BREAK THE [WOUNDS + UNAWARENESS] CYCLE!

My story is a little familiar but with a bit of a twist. I married my wife almost 4 years ago. She moved here from another state. Her only daughter was not happy to say the least. I have custody of my two kids. Her daughter does not like for me to say anything to her. The problem is that her mother has always defended her and taken her side even when she was wrong. My wife (and I am not exaggerating) has NEVER taken my side against her daughter. Her daughter has never been made to apologize EVER. Our latest incident has really got me to thinking I want out of this. My wife bought her daughter a car, pays her insurance, gas, phone, and makes her do nothing at all. She won’t even put her glass in the sink. My wife won’t make her work and will not demand that she do anything around the house. I cannot afford to buy my daughter a car and my daughter just got a job. The rules are different for her daughter and my kids. I have asked my step-daughter on numerous occasions to pull her car down in the driveway and she just will not do it, simply because I asked her. She told my daughter that it is just ridiculous. My wife and I are fighting now because I said something. My wife instead of telling her daughter to pull down yelled at me wanting to know why it mattered. The house is in my name and I make the house payments. My wife is so obsessed with her daughter, gives her everything. She has never disciplined her daughter the whole time that I have known her and to hear her tell it her daughter is the sweetest most wonderful child ever. I read posts about defiant step-kids but most of the time the parents are united. We have been to counseling but it turned ugly when the focus was placed on her daughter. Is there any hope if my wife is not willing to stand shoulder to shoulder with me? HELP!
P.S. do I demand that she pull her car down in the driveway, knowing that it will cause a fight and her mother once again taking her side, or do I keep my mouth shut, let the daughter have her way so as not to rock the boat?

Sounds like the problem is husband-wife communication. If the adults are not on the same page she will naturally read the page her mother is reading (my opinion)