▁P 4 . ▁In ▁this ▁form , ▁output ▁of ▁ ▁was ▁claimed . ▁An ▁automatic ▁transmission , ▁over drive ▁on ▁the ▁manual , ▁and ▁Bur man ▁power ▁ste ering ▁were ▁optional ▁with ▁over drive ▁becoming ▁standard ▁from ▁May ▁ 1 9 6 0 . ▁ ▁Sto pping ▁power ▁came ▁originally ▁from ▁a ▁Gir ling ▁bra ke ▁system ▁that ▁employed ▁ ▁drums ▁all ▁round , ▁but ▁this ▁was ▁a ▁heavy ▁car ▁and ▁by ▁the ▁time ▁of ▁the ▁London ▁Motor ▁Show ▁in ▁October ▁ 1 9 5 9 ▁Gir ling ▁front ▁power ▁disc s ▁bra kes ▁were ▁fitted . ▁ ▁The ▁susp ension ▁was ▁independent ▁at ▁the ▁front ▁using ▁wish b ones ▁and ▁t ors ion ▁bars ▁and ▁at ▁the ▁rear ▁had ▁a ▁live ▁ax le ▁with ▁semi - elli ptic ▁leaf ▁spr ings . ▁ ▁A ▁Mark ▁I - A ▁line , ▁introduced ▁in ▁September ▁ 1 9 6 1 , ▁featured ▁a ▁minor ▁rest yle ▁with ▁added ▁front ▁quarter ▁windows , ▁intended ▁to ▁" ass ist ▁the ▁dash board ▁vent ilation ". ▁Under ▁the ▁metal , ▁the ▁ 1 A ▁featured ▁modifications ▁to ▁the ▁engine ▁mount ings ▁and ▁the ▁automatic ▁transmission ▁and ▁hydro ste er ▁variable ▁ratio ▁power ▁ste ering ▁as ▁an ▁option . ▁ ▁By ▁ 1 9 6 2 , ▁when ▁production ▁of ▁the ▁original ▁Mark ▁I ▁series ▁ended , ▁ 2 0 , 9 6 3 ▁had ▁been ▁produced . ▁ ▁An ▁automatic ▁version ▁tested ▁by ▁The ▁Motor ▁magazine ▁in ▁ 1 9 6 0 ▁had ▁a ▁top ▁speed ▁of