There is generally speaking three ways for the Crown to prove “care or control”.
One way is to simply prove driving (care and control is an included offence). This is not very common but it still can happen. Sometimes it happens based on the defendant’s own testimony. That is why it is very important to say nothing to the police at the scene and while in the police’s custody. It includes admission of being a driver of the car in question. It is also very important to make an informed decision as to whether testify at trial or not.
Another way for the Crown to achieve a conviction would be to rely on a presumption that deems you to be in care and control if you are found in the driver’s seat. You can rebut this presumption by showing that you were in the drivers seat not for the purposes of driving. It usually requires taking the stand and explaining under oath why is it that you were found in the driver’s seat. Typical examples are: waiting for a designated driver and listening to radio or turning the heat on a cold night.
Lastly, the Crown may try to show that even though the presumption does not apply to you (for instance if you were not in driver’s seat or you rebutted the presumption), you used the car or its fittings and equipment in a way which would involve the risk of putting the vehicle in motion so that it could become dangerous.