Psychologist Richard Wiseman of Quirky Mind Stuff posted this perspective illusion in his blog and told us that the cars are the same size. Despite that, our mind stubbornly believes that the car on top are larger - much larger, maybe almost twice the size - of the car at the bottom.
How can this be?
You're looking at a great example of the Ponzo Illusion, which was first demonstrated by Italian psychologist Mario Ponzo in 1911. Ponzo suggested that the way we judge an object's size is highly dependent on its background.
Indeed, you can take a ruler and measure the heights of the three cars (or check out the crude animated GIF below that I whipped out to show the effect) - but even after you *know* that the cars are of the same size, your brain simply refuses to see it that way.
Three cars of the same size parked that way in actual life wouldn't look like they're of different sizes because the car furthest away would be smaller (pixel-wise).
Still a neat effect.