The deduction is irrespective of how you generated the money ... Further gifts are excluded from income (under Title 26 of the US code)
So, yes whether this was a gift from parents, income that you have already paid tax on, withdrawal from in IRA, etc., etc. --- All that matters is that you actually spent the money on medical costs
($ over which you had control that you decided to spend on medical costs) Make sense?
The car is just a vehicle, a conduit. .. could have been a check, a credit card, a debit card. You still spent the money on a deductible medical expense. The criteria for the deduction is that you spent the money on a deductible medical expense ... source of the money isnt an issue.
sorry for the typo ... The CARD is just a vehicle ....