RE air cond . Lot of BS around regarding retrofit . There are drop in replacements for R12 that only require the system be evacuated then recharged ,should only cost $100 max . Even R134a only needs oil change & liqiud line filter replaced , should only cost around $250 . I have done limo fleets & taxis with both , the drop in refrig is a bit dearer so if it needs topping up often go for R134a. Fitting A/C to non A/c car like BmW would be nightmare esp the controls .