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Machine Wars was a short-lived toy series in the Transformers toyline, introduced in 1997. The series was initially exclusive to KB Toys and its subsidiaries, although overstock/unsold surplus eventually appeared at other retailers.
Machine Wars was Hasbro's first attempt at returning to vehicle-formed Transformers after it had revolutionised the toyline with Beast Wars, where all toys had animal alternate modes. The Machine Wars subline lasted only for one wave of toys, which contained twelve toys - six Autobots and six Decepticons. With no TV show or comic book to back the story up, the line generated little interest and sales were so low that the line ended after the first wave. The line also seemed somewhat rushed, with most of the toys even lacking original packaging art (the Basic-sized race car mold used altered art from Generation 2 Laser Rod Jolt, the two basic jets used recycled European packaging art, Optimus Prime's art was altered from his Generation 2 Laser Rod version, and the other three boxed toys used recolored art from their original counterparts).
Although no official Machine Wars fiction was ever made outside the toy tech spec biographies, Hubcap and Prowl did make brief cameos in various Transformers: Timelines stories.
The toys in the Machine Wars subline came in two size classes. The eight toys in the smaller size class were new molds left over from Generation 2, with two toys from each of four molds. The four larger toys were repaints of earlier European-exclusive Generation 1 toys.
The eight smaller toys had a spring-loaded "instant transformation" feature like the smallest toys of the first Beast Wars line also had. These toys were designed to have transparent windows and "light pipe" eyes, but those parts were cast in opaque plastic, much like the first year Beast Wars toys, probably to lower production costs.
Changes from the original European versions
The original European versions of the four larger molds had spring-loaded guns capable of firing oblong plastic bullets, but because of the heightened child safety laws of the United States, the spring-loaded guns were not included in the Machine Wars versions.
The original European Predators had a "scope" system where smaller Predator aeroplanes could be locked onto scopes on the two bigger Predators, and looking through the scope would present a picture of an enemy Turbomaster. This feature was not fully carried over to the Machine Wars versions - the scopes were retained, but they no longer contained any pictures. The smaller Predator planes were not included in the Machine Wars toyline.
- Optimus Prime: Futuristic tractor trailer. Repaint/remold of European-exclusive Turbomaster Thunderclash.
- Sandstorm: Futuristic helicopter. Repaint of European-exclusive Turbomaster Rotorstorm.
- Mirage: Lola T-95 Racing car. Based on a mold prototyped in late Generation Two, but never produced as a toy.
- Prowl: Racing car, shares the same mold as Mirage.
- Hoist: Tow truck. Based on a mold prototyped in late Generation Two, but never produced as a toy.
- Hubcap: Tow truck, shares the same mold as Hoist.
- Starscream: Futuristic bomber aeroplane. Repaint of European-exclusive Predator Skyquake.
- Soundwave: Futuristic missile carrier tank. Repaint of European-exclusive Predator Stalker.
- Megatron: F-22 Raptor. Megatron's blister card had Megaplex's art and vice versa. Based on a mold prototyped in late Generation Two, but never produced as a toy.
- Megaplex: F-22 Raptor, shares the same mold as Megatron. The only toy in the entire line whose name hadn't been used previously.
- Skywarp: Dassault Rafale. Based on a mold prototyped in late Generation Two, but never produced as a toy.
- Thundercracker: Dassault Rafale, shares the same mold as Skywarp.
The four previously unreleased Generation 2 molds introduced in Machine Wars were eventually used in the Beast Wars II and Transformers: Car Robots/Transformers: Robots in Disguise toylines. The line later served as inspiration for the 2013 plotline of BotCon, Machine Wars: Termination. 
- Alvarez, J.E. (2001). The Unofficial Guide to Transformers 1980s Through 1990s Revised & Expanded 2nd Edition. Schiffer Publishing Ltd. p. 128. ISBN 0-7643-1364-9.