Taken from owners manual - ADDITIONAL HEATER
(Multijet versions)
This device enables quick warming up of
the passenger’s compartment in cold en-
vironmental conditions.
The additional heater will switch on au-
tomatically after turning the ignition key
to ON.
IMPORTANT The additional heater
works only with outside temperature be-
low 12°C, engine coolant temperature be-
low 50°C and car battery voltage over
10.25 V.
IMPORTANT Do not park the car over
flammable material such as paper, dry
grass or leaves: fire danger.


So where is it and does my 2.4 prestigio have one?

The additional heater was only fitted as an optional extra to diesel versions. It's a small diesel engine with it's own fuel supply from the main fuel tank, and it's own exhaust pipe. Was usually only fitted to cars destined for cold climate countries. (Scandinavia etc.)

eLEARN suggests it's fitted in the engine compartment. If your car has one, you should be able to see the small additional exhaust pipe and silencer (8 in the diagram below) coming form it under the engine.
.