According to my experience on auotmatic gears, L1 & 2 are not for racing or accelaration, it is true they r 1st and 2nd gear, but their usage is for going up the hill or coming down from hills, as if you r coming down the hills in D position, speed of the car will definately increase, and u will apply brakes a lot, which will result in brake failure, to avoid brake failure and frequent use of brakes, L1 and 2 are used, to control the speed of the car, as u do in manual gear.