(In Car) SatNav Help

[Altissimus]

Hi Folks,

Struggling to understand the world of in-car SatNavs at the moment, and could do with some help please.

I'm basically trying to understand, *for cars built between 2008 and 2011*:

a) which manufacturer's in-car SatNavs can do 7 digit postcode entry
b) which manufacturer's in-car SatNavs can do 7 digit postcode entry once you get the dealer to update them to the latest firmware
c) which systems are any good.

Can anyone help me here please?

Thanks,
A