Mechanic here.
Read the manual, but I bet it takes premium.
If the manual calls for premium, never use lower grade gas if you are paying for it (assuming normal gas prices). Nothing bad will happen, but the ECU will retard the engine timing to prevent predetonation (knocking). That will drop both power and fuel efficiency. You'll lose more fuel efficiency than you gain in the price difference of regular vs premium.
On the flip side, never use higher grade gas than is called for. The higher the octane, the lower the energy in the gasoline, so higher octane gas also causes slightly lower fuel efficiency.