We all want to maximize every yard we can get out of our driver, so contact is very important. Using golf-specific impact spray (or you can simply use foot spray), spray the face of your driver. This will give you immediate feedback as to your contact position with the driver.
Knowing that hitting the ball in the center of the face is the ideal result, we can better diagnose issues within our swing or path based on the ball flight. Gear effect on drivers will have an impact on the ball flight, so knowing where the ball hit on the face and how it impacted the shot will make understanding our ball flight that much easier.