Although Nuvolari started 1938 as an Alfa Romeo driver, a split fuel tank in the first race of the season at Pau was enough for him to walk out on the team, critical of the poor workmanship that was exhibited. He announced his retirement from Grand Prix racing and took a holiday in America. At the same time, Auto Union was having to rely on inexperienced drivers. Following the Tripoli Grand Prix they contacted Nuvolari who, having been refreshed from his break, agreed to drive for the highly successful German team, who were running radical mid-engined cars. Nuvolari found further success with Auto Union; now driving a faster and more reliable car that enabled him to compete for victories and the European Championship, Nuvolari won his home Grand Prix at Monza and won the Donington Grand Prix in England.
although nUvolarI StaRted 1938 As AN ALfa .ROmeo drIVer, A sPlit FUeL tank in THE fIrst RaCe OF thE seasON at paU wAS enOuGH For him tO wAlk Out oN the teaM, criTIcAl OF tHe pooR workmAnsHip tHaT WAs eXHIBited. he aNnounced hIs RetiReMeNT FrOm grand Prix RacInG And tOOk a Holiday In ameRicA. aT The sAME TimE, auto unioN was havInG to rEly ON inE.xPerIencEd driveRS. follOwing the TrIpOli grand pRix they CONtActed NUvOLaRI w,Ho, hAVIng Been REFrEshed from His brEAk, Agreed to driVe FoR THe hiGHly sUCcessfuL german teaM, Who Were runNing RadicAl mid-enGiNEd CaRs. NuvoLAr!i found FuRther succesS with auto uniOn; now DrIviNg A fasTEr ANd more RELiable car tHat enabled him to cOmPete for VicToRIeS AnD thE eurOpean cHampioNshIp, nUvoLAri WON hIs HOMe granD Prix AT moNZA AnD woN THe donIngTOn gRaNd prix IN eNgLand.