▁and ▁this ▁was ▁another ▁successful ▁model ▁for ▁V aux hall . ▁▁ ▁The ▁overall ▁strategy ▁for ▁V aux hall ▁continued ▁to ▁be ▁to ▁make ▁smaller ▁models ▁with ▁the ▁latest ▁engineering ▁develop ments . ▁V aux hall ▁and ▁G M ▁management ▁planned ▁a ▁completely ▁new ▁three - model ▁car ▁range ▁which ▁would ▁use ▁cutting - edge ▁un ib ody ▁construction ▁instead ▁of ▁the ▁traditional ▁body - on - frame ▁design . ▁The ▁first ▁mass - production ▁un ib ody ▁car , ▁the ▁Cit ro ën ▁Tra ction ▁Av ant ▁began ▁production ▁in ▁ 1 9 3 4 , ▁the ▁same ▁year ▁that ▁design ▁work ▁on ▁the ▁new ▁V aux hall ▁range ▁began . ▁As ▁well ▁as ▁design ing ▁an ▁entirely ▁new ▁car ▁body , ▁this ▁change ▁required ▁major ▁expansion , ▁renew al ▁and ▁invest ment ▁in ▁the ▁L ut on ▁factory ▁as ▁well ▁as ▁a ▁significant ▁expansion ▁of ▁V aux hall ' s ▁engineering ▁and ▁design ▁staff . ▁The ▁first ▁of ▁the ▁new ▁models ▁was ▁released ▁in ▁September ▁ 1 9 3 7 . ▁This ▁was ▁the ▁H - type ▁ 1 0 - 4 ▁( the ▁model ▁number ▁referring ▁to ▁its ▁ 1 0 ▁tax - hor se power , ▁four - cy l inder ▁engine ). ▁This ▁was ▁the ▁first ▁truly ▁small ▁V aux hall ▁in ▁many ▁years . ▁As ▁well ▁as ▁its ▁advanced ▁un ib ody ▁structure ▁- ▁a ▁first ▁for ▁a ▁British ▁sal oon ▁car ▁- ▁the ▁ 1 0 - 4 ▁also ▁featured ▁an ▁overhead ▁val ve ▁engine ,