Manufacturers began to replace V8 engines with straight-6 engines and V6 engines with straight-4 engines, while V8 engines became smaller. This was a part of a trend toward higher efficiency engines with fewer cylinders, but the same power output as previous larger engines as fuel economy standards became more stringent. A result of modular engine designs was that straight-6 engines could be built on the same assembly lines as straight-4 engines, while V8 engines smaller than previous V8s could be built with the same components as straight-4 engines in the same family.