heated seats..

[C.A.R.]

306s had heated seats as an option on the continent (I think it was part of a Winter Pack which got you headlight washers too)

The heated elements are available on the aftermarket to run from 12V, so it would just be a case of stripping the seat covers off and installing them. My old Cabriolet had an aftermarket install of heated seats which were amazing, the switches were down by the handbrake.

You can even buy the genuine switch panel from Peugeot but it's expensive and god-knows whether it would ever arrive -

6552X8 - Heated Seat Switch-£33.04 (need 2)
7587WW - Switch bracket - £5.06 - Goes where rear ashtray / rear window switches are
7587YP - Switch Bracket set - £29.76 - Goes above the above bracket, you get 3 different types included dependant on the accessories you have in your car

So it could be a very nice OEM install, but it would be expensive. Better bet is to buy them from eBay France or Belgium...