Barca have swept all before them in recent years, winning 12 trophies since Pep Guardiola took charge in 2008 including three successive La Liga crowns and two Champions League titles, and they have started this season in similarly ominous fashion.
They currently sit atop the league standings with 14 points from a possible 18, while in their opening three matches at home they have thrashed Osasuna 8-0 and beaten both Villarreal and Atletico Madrid 5-0.
The 55-year-old Cuper, whose Racing side are stuck in the bottom three of the standings and still looking for their first win, admits he has not seen anything that compares to the current Barca side.
"Since I've been in the world of football, I've never seen anything like it. They are excellent. The best team in the world, and a long way from the others. They have it all, they are ground-breaking," the Argentinian was quoted as saying in Spanish newspaper Sport.
"The strikers are in midfield and vice-versa, or the defenders are the most dangerous attackers. Someone tell me if (Sergio) Busquets is a defender or midfielder, or if (Lionel) Messi is a winger, striker, playmaker or midfielder, not to mention (Javier) Mascherano.
"I've always said that perfection doesn't exist, but this Barca is as close as I've ever seen."
Cuper, who counts the likes of Inter Milan, Valencia and Parma among his former clubs, also hailed Guardiola's willingness to promote players from Barca's famed youth system.
"If Barca needs any player from the youth team, they pick them, they train with the first team, they put them into play and they play as if they've had three or four years with the squad. This, which only Barca can do right now, is admirable and at the same time incredible.
"For a team of this level to play, usually, with six or seven players from their youth team, and who can even play with 10 or 11, is unique. "