Mezera took up a Physics course at university after leaving school and joined their ski team, escaping to Hungary during an event and defecting to Austria via Belgrade.

Mezera finished 5th in the 1984 Formula Ford Driver to Europe Series, and won the 1985 Motorcraft Formula Ford Driver to Europe Series driving the Dalcar Reynard FF83 prepared by motorsport enthusiast and team owner David Haydon (with engines supplied by the Frank Gardner run JPS Team BMW).

During 1988 while working as a driving instructor in England, Mezera was able to secure much needed parts for the Ford Sierra RS500 Group A touring car team run by Frank Gardner and Tony Longhurst.

As it was Gardner's protest at Bathurst in 1987 that had led to the disqualification of Ford Europe supported Eggenberger Motorsport Sierras and caused them to lose the 1987 World Touring Car Championship to BMW, Ford did not want to supply parts to Tony Longhurst Racing team manager Gardner, and Mezera was asked to buy the needed parts for the team.

This led to racing a Porsche 962 for fellow Aussie Vern Schuppan in the All Japan Sports Prototype Championship and a drive in the 24 Hours of Le Mans in 1990 finishing 15th with co-drivers Eje Elgh and Thomas Danielsson.

He was briefly part of John Trimbole's Daily Planet Racing before starting his own team in 1998 with the help of Derek van Zelm and on limited budget ran in the V8 Supercars Championship from 1998 until 2001.