 Ramba uchiverenga ndima ino - Zwolsman akakwikwidza muWorld Sportscar Championship muna 1991 achipedza ari 6th overall muvatyairi, achimhanya timu yake Euroracing ine chassis kubva kuSpice Engineering. Akaedza zvakare muna 1992 achiisa a hrefLola20T9210Lola T9210a, asi akakundikana kuwana poindi. Zvisinei, chikwata chake cheEuroracing chakapedza chiri chechishanu mumakwikwi aya. Nhevedzano yacho yakapetwa gore rakatevera racho. Akakwikwidza kubva muna 1990 kusvika muna 1992 mumaawa makumi maviri nemana eLe Mans, aine mugumisiro wake wakanaka muna 1992apo akabatana naHeinz-Harald Frentzen naShunji Kasuya kuti vapedze vari 13th. Muna 1992 akakwikwidzawo muInterserie, achikunda mujaho mumwe chete uye achipedza 10th muvatyairi. Mwanakomana waZwolsman Charles Jr. aizotevera baba vake mumitambo yemotokari, achikwikwidzawo muLe Mans pamwe neFormula Three neChamp Car. 