At one point we were switching between driving a gas-powered Taurus and an older diesel Mercedes sedan, which provided very different driving experiences. Because the Benz sounded like a tractor, it was rare that we got even close to putting regular gas in the tank. Though modern diesel sedans aren't common over here, the advancement in technology means that you could accidentally put premium in your oil-burner. What to do?
If you're really lucky, you've not started your car and can thus get it drained by a professional (or a trusted friend) for a decent price according to the lads at MotorTorque. This is the easiest solution and the best way to avoid serious damage.
If you've only put in a tiny amount it may be possible to dilute the gasoline with diesel, but this is highly risky and should only be attempted in older vehicles that don't use high-pressure injection systems. I.E., don't try this in your new Bluetec E-Series.
If you've put more than a sliver in and started the car you're running the risk of damaging the fuel pump, fuel-injection system and washing out all the lubricant in the car. And that's in an older car. If you're car/truck is using a common-rail diesel system you could be looking at major engine destruction (that may not be covered by your insurance).
In this case, an ounce of prevention is worth a gallon of cure/diesel. Make sure to clearly mark your gas gauge, the inside of the fuel door and the fuel cap with the words "DIESEL FUEL ONLY," especially if your ride gets borrowed frequently.
As always, consult a mechanic before you do anything stupid. [MotorTorque]