The oil filler cap on a mercedes-benz slk 320 is stuck is this a problem with this car?

No! Its not the car's fault at all! Just get some butter and slide it off! Kidding, but you cant fill it if it's not able to be filled with oil! Just drive it as long as you can, and then see a carman. If he cant fix it, you're screwed. But you can buy a new one! Go to: automotive.com or you can go to carsdirect.com. Thanks for asking!

-Griffin