Holzer began karting in 2003 and entered Formula BMW ADAC in 2004, competing in the series through 2006. He won the Formula BMW World Final in 2005 and finished third in the ADAC championship in 2006, scoring three race wins that season. In 2006 he also served as a test driver for BMW Sauber in Formula One. His attempt at the Formula Three Euro Series in 2007 produced no championship points, and he moved decisively towards GT and sportscar racing from 2008 onwards.
Holzer signed with Porsche as a junior works driver in 2008, combining a Porsche Supercup campaign with VLN appearances for Manthey Racing. He continued in FIA GT Championship events and VLN in 2009 before being elevated to full Porsche works driver status for 2010.
In 2010, Holzer finished as runner-up in the FIA GT3 European Championship with two victories. At the 24 Hours of Le Mans that year, he drove for BMS Scuderia Italia alongside Richard Westbrook and Timo Scheider, finishing third in class in GT2.
In 2011, Holzer drove a hybrid-powered Porsche 911 for Manthey Racing to an outright victory at the Nürburgring 24 Hours — a significant result in that the hybrid car competed across the full field classification against conventional GT machinery and took the overall win. He also contested the Le Mans Series for Prospeed and made partial appearances in the American Le Mans Series with Flying Lizard Motorsports that season.
Holzer raced the full American Le Mans Series season in 2012 with Flying Lizard in the GT class, and simultaneously ran in the International GT Open for Manthey. In the latter series he won three races and finished as vice-champion in the Super GT class.
In 2013, Holzer joined Paul Miller Racing for the American Le Mans Series as a Porsche works entry. For 2014, he drove for Team Falken Tire in the GTLM class of the IMSA SportsCar Championship and won the Petit Le Mans. He also represented Porsche Team Manthey in the FIA World Endurance Championship's LMGTE Pro class, sharing with Frédéric Makowiecki and Richard Lietz and finishing third in class at the 24 Hours of Le Mans. Porsche dropped Holzer from its factory roster at the end of 2014.
After leaving the Porsche programme, Holzer continued in GT racing. In 2016, he joined Bentley Team Abt for the ADAC GT Masters. In 2019, he contested FIA WEC LMGTE Am rounds with Dempsey-Proton Racing. His most significant result in the post-works period came in 2020, when he won the SP9 Pro-Am class at the Nürburgring 24 Hours with Huber Motorsport. He entered the Nürburgring 24 Hours with Dinamic GT in 2024, finishing twelfth, and with Hankook Competition in 2025, placing fourth in Pro-Am. In 2026 he continued racing in the Nürburgring Langstrecken-Serie with Manthey Racing.
Gallery · 4 related images
