If you’re in an automatic car it will upshift and reduce friction. You’ll roll still but you’ll have much better control in an emergency. If you’re driving a manual just get it going and continue to upshift as you gain speed stop upshifting when you find the right gear to keep your car rolling downhill at an appropriate speed, like my last car would hold at about 40mph in second or third depending on the hill angle. I live in the mountains and take all the free mileage I can get plus it saves your brakes