Many of the sensors use a 5 volt signal, not 12 volts. Bentley manual and BMW Electrical Troubleshooting Manual on CD give the test procedures. On a 1993 325i, which I think is similar to 525i, I measured 5V at the TPS connector pin 3 to earth, which according to the ETM is correct. Your reading of 4.96V seems to be close enough.
bill g