Hugenholtz's father, of the same name, was a Protestant minister and peace activist who moved his family to Purmerend in 1918 and Ammerstol in 1924.

[1] Hugenholtz and his wife, Marianne Sophie van Rheineck Leyssius, were involved in a car crash in Zandvoort on January 10, 1995.

[2] Hugenholtz designed a variety of circuits used for Formula One which have been praised for their challenging nature and innovative features.

[1] Such a concept was ultimately perfected for oval tracks (and some road courses) in the early 2000s in the form of the SAFER barrier.

He was involved in the stillborn projects of the Dutch Barkey (1948) and Delfino (1989) cars, the latter based on the Alfa Romeo Alfasud chassis and drivetrain.