I helped my mates buy a 126p recently but they didn't get very far on their road trip... According to them the gears failed fairly suddenly after a few hundred kms of mostly highway driving. "it was like the gears were in neutral but grinding a bit and not providing any power"
From the sounds of it I'm thinking clutch failure or clutch cable failure?? Maybe loose linkage at the shifter - does that ever happen? It sounds like transmission wasn't fully shifting into gear.
Could it be a gearbox self-destruct if it ran out of oil?
the car has sadly been abandoned in a small town in exchange for a ride to the train station lol
..but I want to make sure I can bring spare parts next time!!