Hello,
I reside in the US, but not a resident/citizen. My mother wired me money from overseas (she is non US resident) for purchase of a car. I purchased the car for her by using up the whole amount she wired.
Are there any tax implications for me? I heard that if more than 10K is wired to a US account, IRS may flag that transaction.
If I keep all the documentation for the car purchase (bill of sale, bill of lading etc), do I need to worry about anything?

Not really. There is a form that should be completed at the bank to identify the source and purpose of the funds, but if the IRS does track you down to ask about the wire transfer, you have sufficient to show what you used the money for.