Starting the car

Is it detrimental to step on the gas peddle while turning the key to start the car?

Not really detrimental, unless you don’t let up on it quickly enough and you race the engine when it’s just been started, but completely unnecessary. Modern fuel injected engines can start without help from the throttle.

If your car is fuel-injected, don’t step on the gas peddle before starting. If it has a carbureter, step on the pedal to give it some gas before starting.
It’s not detrimental to give a fuel-injected engine some gas before starting. It’s just a waste of fuel.

Pressing the gas pedal on a fuel-injected car when the engine is not running doesn’t waste any fuel, just a useless gesture. Holding the gas down when starting a fuel-injected car is unnecessary and may cause excessive wear if the RPMs are allowed to run too high at start-up before the oil has a chance to circulate.

It may actually make the car harder to start. There is absolutely no need to do this.

I wouldn’t. They designed it to be started a certain way. Why mess with that?

I think you’ll discover that we’ll all be in agreement that it does no good and may even be detrimental if, as others have said, it causes you to rev the engine before the oil pressure is up.

Fuel injection does not inject any gasoline when the engine is not turning.