Just a curiosity with what is most likely the cause here - dodgy PTU/Starter/Flywheel/cabling?

 

My 300 always, but always takes two times to start. Wind it up once, let it wind down then try again and it starts. It's never gotten worse or better but it's frustrating!

how long do you try to start it? Mine takes ages to start however my compression is very low

When you are about to start it, switch the ignition on and with the door open listen for the fuel pump pressurising the system. You should hear a faint buzz from the rear of the car as it runs then silence when the system reaches pressure. If it takes more than a few seconds before it stops then it could be fuel draining back from the injectors that is the problem. Even if you cant hear it operating just try having the ignition on for 10 seconds or so before you switch on the starter. If it then starts instantly your on to it.

I can't hear the fuel pump at all unfortunately but then that could be my poor hearing.

 

Tried the above to no avail - this is funny though

1. Try to start car - starter whirs (no matter if I leave it spinning for 1 sec or 15 sec)

2. Try to start car - starts straight away.

3. Turn off

4. Try to start again, exactly the same as above.. again and again and again always 2 times to start!