The Scottish DJ splashed out on the flash vehicle for the 'How We Do' hitmaker - who currently resides in London - in order to encourage her to pass her driving test before she moves into his Beverly Hills mansion with him.
The 23-year-old singer has been taking back-to-back lessons with her instructor to ensure she gains her licence as soon as possible.
A source told The Sun newspaper: ''Rita's never needed to worry about getting around before - it's either taxis, the Tube or walking.
''That's not the way it happens in LA. Unless you have a car, doing anything is impossible.
''She doesn't want to have to rely on Calvin to be designated driver.''
Calvin asked Rita - who is currently filming 'Fifty Shades of Grey' in Vancouver - to move in to his home in a bid to stop their hectic schedules destroying their romance.
The pair sparked rumours they had called time on their 10-month relationship in December following reports they had spent the festive season arguing.
However, they put a stop to the speculation last month when they arrived at the Grammy Awards in Los Angeles together.
The actress spoke about raising her 11 year old daughter Matilda in the wake of Heath Ledger's death eight years ago.