Robotech: The Movie was primarily made from the first episode of Megazone 23, which was notable for being the first OVA -- Original Video Animation (basically, 'direct to video' title) released in Japan.
While Megazone 23 does feature a gorgeous idol singer designed by Haruhiku Mikimoto (as with Lynn Minmay in the Macross portion of Robotech), and motorcycles which transform into robots (similar to those in the Mospeada section of Robotech) .. the storyline had little common ground with the events Carl Macek had established in the Robotech TV series.
Since it didn't have to conform to broadcast standards in Japan, Megazone 23 featured quite a bit more sex & violence than the three anime shows Robotech had been cobbled from. It also ended on a rather dystopian 'downer' note .. so, Mr. Macek commissioned a newly-animated 'happier' ending scene!