Baron Munchausen would like to have a word

More weight = more magnetic

I don't know.

The actual metal content varies. With plastic bumpers, aluminum condenser/radiator, composite support pieces, the actual amount of magnetic metal may be quite minimal, and there's practically no vehicles that have so much metal in their front end to compare to a slab of metal on the outside.

Try using a magnet on a can of coke.
"But it's made of metal" he says.

He's dead

The brake pedal slides an opposite side magnet closer to you.

Use an electromagnet

Play an Insane Clown Posse song and the magnet stops working.

Where I'm from this exact picture was easily recognized as a funny joke

So the vehicle just needs turning around for this to work then or.....?

Newton's third law. Every action has an equal and opposite reaction.

Basically what that means is if the magnet is exerting some amount of force on the truck to pull it towards it, the truck is exerting the exact same amount of force on the magnet in the opposite direction to pull the magnet closer to the truck. This is why when you let go of two magnets they fly towards each other instead of one staying still (unless you hold it still) and the other flying towards it.

If the arm in the picture could bend, the magnet would just stick to the front bumper. If it couldn't move, the magnet would pull on the plate, but that would be cancelled out by the plate pulling on the magnet. They're trying to attract each other, but neither of them can move, so it just stays still.

Now, if the magnet was attached to a different truck, and that started moving, it would pull the truck along just fine. If the second truck was in neutral, it'd roll backwards and the two trucks would meet in the middle. But if you wanted them both to go, you'd have to turn on the engine in the second truck, and you've effectively just invented the world's least reliable tow hook. You can't cause a car to accelerate without some outside force (the second truck's engine) pulling it along.

Newton's third law also applies to gravity. When the Earth's gravitational pull makes something fall to the ground, that something actually exerts the same amount of force pulling the Earth towards it. The earth is several orders of magnitude heavier, though, so it doesn't move very much. Gravity from the moon pulling on water in the ocean does create the tides, though.

The magnet pulls the truck to the right. The truck pulls the magnet to the left. They both have the same amount of pull. No one wins this tug-o-war.

Because the magnet is attached to the truck bed, so the bumper is being pulled forward and the bed pushed back, and the forces cancel out to 0.

Newtons laws of motion, most clearly the third.

"If two bodies exert forces on each other, these forces have the same magnitude but opposite directions."

In simple terms: metal is just as much attracted to magnet as magnet is to metal, this is fundamental and doesn't change under any circumstances.

So the force driving the car forward is exactly equal to the force driving the car backward, and you can't have one without the other.

go faster

More horsepower. Duh