Sondermann began racing karts at the age of sixteen and soon moved up to the Brazilian Formula Renault championship for 2002, in which he competed for two years with mixed results.

He competed in the second tier of the series, known variously as Stock Car Light, Stock Car Copa Vicar and latterly as the Copa Chevrolet Montana from 2006 until 2011, winning four races in total and with a best finish of third place in the championship in 2007, a year soured by the death of his team-mate, Rafael Sperafico, in the season finale.

In 2010, he competed in seven races of the premier Stock Car Brasil division, scoring six points and finishing in 31st place in the championship.

(key) (Races in bold indicate pole position; races in italics indicate fastest lap) † As Sondermann was a guest driver, he was ineligible for points During the first race of the 2011 Copa Chevrolet Montana season, held in heavy rain at the Autódromo José Carlos Pace, Sondermann was hit by several cars and ultimately by Pedro Boesel at the fast Curva do Café before the start-finish straight.

He was extricated from his car and transferred to hospital in a coma after having had cardiac arrest, where he later was diagnosed brain-dead.