complete new (or second hand) heating vs propex

Might be OK in a new Audi, but there's no way your alternator will keep the battery charged well enough to power anything good ;-)
Burning stuff is an excellent way to provide heat, electricity is a great way of providing light.

 

inclined to agree....2KW fan heater @12v draws 166Amps...the latest propex is rated at 2KW

 

I may look into what the unit looks like as u never get cold in a Audi !!

 

If you're running a dynamo, you'd be using the energy in your battery 4.37 times as fast as you COULD keep it charged (if your dynamo was on full chat)
If you're running an alternator, you're using the energy at 3.02 times the rate you can keep it charged.
Electric only heaters are not worth considering, you need to burn stuff.

 

like this one? http://www.amazon.co.uk/Audi-4x4-12v-Heater-Defroster/dp/B006M023C0

 

You would be better off eating beans