Basic N-MOSFET Circuit Simulation Results
The STP100 has an on resistance of 0.0035 Ohms.  So the real world was not driving a 0.01 Ohm load to near 0V.  The best it should have said was about 3V.  The transistor you have made in the model is not capable of the current needed to lower the voltage at the mosfet end to 0V.  Change the Beta in your model to 1000 and you'll get there.  So the problem is too small a transistor for too big of a load.