>>248694
>Wait what about the ignition and the parking brake and the seat belt and the door?
Well, that's all a given. I'm just saying to not start on a gear higher than the first.
>I don't understand, could you please clarify?
Each gear is designed for a specific speed range. Say, first is for 0-15 mph, second is for 10-25 mph, third is for 20-40 mph...
If you're going too fast for the current gear, the engine starts working too hard and you will hear it straining, at which point you should shift to a higher gear. If you're going too slow for the current gear, the engine is working too soft and you will hear it struggling, at which point you should shift to a lower gear. You may also feel the car vibrate.
If the gear is too high (you're going too slow) the car may stall, and if the gear is too low (you're going too fast) the fuel consumption increases. And overall, using inadequate gears wears down the car in the long term.
>Why what will happen?
It can cause significant damage to the gearbox and other components. Autos generally don't let you do it. But some modern manuals with safety features may prevent you from doing it too.