HeHeHehehe; you have just displayed your ignorance of not only PHYSICS but also of DRIVING.
First of all Ms.Sanjevani; one does not lose speed on a turn while driving due to changing gears! One is going to lose speed on a turn, so one needs to change gears i.e. shift into a lower gear to regain momentum (and torque) and recover the lost velocity. A deficient driver shifts after (or into) the turn. The smarter driver shifts before the turn, by which he also gains/maintains traction. Simple PHYSICS.
Just to enlighten you, just look at how F1 and other racing drivers take turns/bends......That will also explain why race-cars (and premium performance cars) have paddle-shifting for rapid-fire shifting.
Now about Aircraft: Pilots use a similar technique sans gears........to achieve the same effect. Again Simple PHYSICS! Its related to ENERGY and the "bleeding" thereof.
Now find out what they do...........