Flat engines are horizontally-opposed piston engines, and this group includes Boxer engines, but not opposed-piston engines like the Cummins 14.3L Advanced Combat Engine (ACE) designed to power tanks.
Subaru nearly lost a generation of buyers over one fixable flaw.
The plastic cover of a Subaru Boxer engine showing the Subaru constellation logo - Topuria Design/Shutterstock Flat engines are horizontally-opposed piston engines, and this group includes Boxer ...