There is a difference in meaning between these two, at least where I live in the United States. To "park on the road/street" means to park along the side of the road/street, near the curb. To "park in the road/street" would mean to park so that all or part of the car is blocking the road so that other cars cannot easily pass. If someone parks "in the road," we would call the police and the car would be towed away. Or if a police officer sees this, they will call to have the car towed away, or they will install a locking device called a "boot" that will prevent the owner from driving the car without calling a phone number, paying a fine and having the boot removed. Sometimes, a driver will park "in the road" if all of the parking spaces along the curb are occupied. The person will park "in the road" to wait for someone who they believe will be coming right out to ride with them. Or they might even leave the vehicle parked "in the road" with the hazard lights blinking to run into a store and make a quick purchase. This is illegal, but people do it. It is called "double parking." I've included an image. Most cars have parked "on the road" (i.e. in a safe parking spot along the curb). The black car close to the camera, however, is parked "in the road" (i.e., he is double-parked). You will notice that there is a yellow "boot" on the back wheel. The police saw this car and installed the boot, because he is parked illegally.

Both I would say can be used -:)

Both are fine to use, regarding their diffrence in meaning !

The Beatles have a song…why don’t we do it in the road. I would say I’m standing on the road to Madagascar. Where is your car parked? On the road or on the side walk? Its in the middle of the street!

You can't park on the road