Translation:How much does a driver cost for a day?
"How much does the chauffeur cost per day?" should be an accepted alternative per https://en.wiktionary.org/wiki/%E5%8F%B8%E6%A9%9F#Chinese.
Side Note: I'm improving my English too. I just realized that I've never written the word "chauffeur" before after initially misspelling it.
I did per day before and got it rejected. Then I put for a day and it's rejected. What gives?