I want to be able to leave my car running with it locked for my Pets when it is too hot outside. Am I able to do this?

C300W 2021

Sort off. I think you can lock the doors using the mechanical key inside of your fob, but that's a bit cumbersome, because you have to pop the plastic cover of the lock first to get to it. Not a 100% sure, but the engine probably stays running if you do that. The only other option is to lock the car, then use the app to remote start the engine. It will only run for 10 minutes, though, and then turn off automatically and you can only remote start the engine twice before it has to be manually started again. This is not really something you do in a modern ICE car, though, and bystanders may not appreciate the noise and exhaust from your engine. This is something that EVs can offer such as Tesla's Dog Mode.

And the bystanders are almost certain to call the cops on an unattended pat in a car, even if the engine is running. They may not even hear the engine running in a crowded, noisy area such as a mall parking lot. That goes for Tesla's Dog Mode, too. Maybe not with signs in the auto windows ...

Yes especially with a Mercedes engine that is meant to have low noise. Where I live, people are actually encouraged to smash your windows if they see a pet in the vehicle alone. I am glad OP doesn't have to face that issue. I thought of recommending tinting windows then do what superswiss suggested and keep engine running that way but I am worried that your pets are going to make noises when people walk past. May I please ask if where you are going to specifically said no pets allowed or they are more lenient and your pets can be carried with you with a bag with ventilation but just not on a leash?

And cycles OFF from time to time!