be in high gear

1. Literally, of a vehicle, to be operating at a high or the highest gear. The car started to stall going up the hill, and I realized that it was still in high gear. Is the car in high gear? Why is it making that awful sound? A: "Is the car in high gear?" B: "I have no idea, this is my first time driving a stick shift!"

2. By extension, to be operating at the highest, fastest, or most efficient level. We've expanded our development team and are in high gear working on our next project. Construction is in high gear all around the city as it prepares for the upcoming Olympics. We had to delay opening the factory for two weeks because of a health violation, but we're in high gear now.