"Tim Streater" wrote in message
.. .
If the alternator is capable of starting the car why don't they just
remove
the starter motor and save the cost and weight?

Which is what our Auris hybrid does.

Ah I didn't realise the Auris uses the alternator to start the car from
cold. I presume if the fan belt breaks you are utterly buggered because you
can't restart the engine (if it's stopped) to be able to drive (with the
engine using on battery rather than alternator power for its spark) to a
safe place to wait for Mr RAC or Ms AA to tow you to a garage.