Yeah I'm sure he didn't put petrol inside, the car would run rough on petrol, but the engine sounds really nice and smooth.
Thanks again for the tips guys.
Hey thanks for all the help!
After reading the thread "C250 TD top speed 80mph?", I solved the problem! The MAP sensor cable wasn't plugged in. I found the cable under the water unit. I plugged it in and didn't see any difference until I drove it a few miles... now it has proper turbo power!!! Vrooom vrooooom!