You're going to hear from one group saying "OH MY GOD that's SOOO dangerous" and another group saying NO PROBLEM.
All I can tell you is, I've been doing that since I started driving, and that's a LOOOOOOOOOOOONG time. Gas was 25 cents a gallon back then.
Don't drive with both feet. Pivot with your right foot. If you drive with both feet you'll run into the problem of pressing both pedals at the same time and looking like an idiot to the driver behind you.
Reasons to use one foot on automatic transmission cars.
1. If you transition to a manual transmission, you don't have to retrain your left foot to operate the clutch.
2. Some people "hover" their left foot over the brake pedal. They may inadvertently be applying a little brake pedal pressure. Not enough to actually apply brakes, but enough to activate your brake lights. The drivers behind you won't know when you actually apply your brakes (no change in brake light intensity). Theoretically, you would be operating a car with faulty brake lights (you could be cited but not likely).
3. In a panic stop, you could apply gas and brake at the same time (I've seen it in a demonstration in driver's ed). That would lengthen your stopping distance significantly almost guaranteeing a collision. Training yourself to drive with only the right foot guarantees you won't apply gas and brake at the same time.
4. Reaction time is not significantly reduced. If you rest your left foot on the floor, your reaction time could actually be a little longer (in theory).
5. Your road test would end in a failure.
Do not drive with both feet . All is good when normal ,but in tricky situation big chance you will panic and step on both if you use both feet .
It is not a good idea for several reasons. Short answer: just use one foot.
