One of the most amusing things a person can experience is when a car in neutral appears to go uphill when its brakes are released. can this really happen? note that the car is an isolated system with no external force acting on it.

No, it cannot happen. It's just an illusion.

Explanation:

We can blame the horizon for this. Generally people is used to seeing the horizon as horizontal (this is perpendicular to the force of gravity). That's why our brains take the horizon as a reference point. The horizon will help our brains tell when something goes up or down.

What is really going on in these particular roads, is that the horizon is inclined downwards, letting our brains think that the road is going upwards, when it's actually going downwards. (See attached picture).

According to physics, gravity always goes in the direction of the center of the earth (downwards). It happens like that everywhere on earth. When the horizon is inclined downwards, our brains think it is horizontal when it actually isn't. It gives us then the illusion that there is a misterious force pulling things upwards and that's why it might appear that the car is going uphill, but it's actually going downwards as usual.

Unless there is an external force (besides gravity) acting on the car, it is impossible that the car will move upwards on a road. That's why the answer is that it cannot really happen, it's just an illusion.

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