What is the point of getting the golden vehicles in jetpack joyride?

Other than the fact that you get to ride shinier vehicles, there is a secret achievement that is unlocked when you purchase your first gold vehicle (which you've already done). Its called Blinged Out.

Gold vehicles should be no different from the regular ones.

The Golden vehicles are no different aside from the visual effects (they are reflective gold all over and sparkle a bit). There's no functional difference, the only practical use is to get an achievement (at least I believe there was an achievement for buying one of them).

They shouldn't take up more of the screen either though, They're just re-skinned.