Her major career victories also include a gold medal in the individual time trial competition at the 2007 UCI Road World Championships in Stuttgart and a silver medal in the road race at the 2000 Summer Olympics in Sydney.

She finished 1st in the year-end UCI world class rankings in 1997 and 1999 winning the 1999 La Flèche Wallonne Féminine in the process.

Kupfernagel captured the Emakumeen Bira cyclo-cross race for three consecutive years from 1997 to 1999.

She seemed to be the favourite for the women's race at the 2009 UCI Cyclo-cross World Championships in Hoogerheide, but she was not able to defend her title as Marianne Vos beat her during a sprint finish and left her with the silver medal.

[1] After three and a half years out of competition she participated in the German cyclo-cross championship 2019 at the age of 44 finishing the race in second place.