All I remember is a woman in a convertible coming through a portal to a parallel universe. Lots of sand/desert. Running into a Conan/Beastmaster mostly loincloth outfitted guy.
This certainly could be Beastmaster 2: Through the Portal of Time, from 1991. Take a look.
Dar, the Beastmaster, learns of a previously-unknown half-brother, Arklon, who plans to conquer the land with the help of a sorceress named Lyranna. Both escape to present day Los Angeles through a dimensional portal. Dar and his animal companions, Ruh, Kodo, Podo and Sharak, must follow them through the portal and stop them from obtaining a neutron bomb. During his visit, Dar meets a rich girl named Jackie Trent, and they become friends.
There is plenty of sandy terrain in the fantasy world part of the story; Marc Singer returns as the Beastmaster (looking, Joe Bob Briggs pointed out when they showed the film on TNT MonsterVision, quite a bit more buff than in the first film); and the female lead, Jackie Trent, has a really sweet convertible.
The whole thing is on YouTube. Here's the scene with the sports car in the desert.
Could it be Outlaw of Gor? It was featured on Mystery Science Theater 3000. That had two men who were transported to another dimension but there were also two female characters, evil and good. Much of it was shot in the desert.
One scene famously repeats characters saying, "Cabot" about a thousand times.