I have two elder sisters and believe me it can get really hectic driving them, Elder siblings can be like that and I think your mom just reverberates whatever your sister is saying only because she will have more faith in her; because she’s elder to you, it’s a lame reason but for parents it is like that.

If I’m not mistaken you have not been driving for a long time. It’s going to be an effort but the next time they complain just try to not react and keep on driving how you drive, the more you react to their advice the more they’ll poke out every little detail. Everyone has their own style of driving and they just need to adjust to yours.