The Subaru Rex was a keicar automobile produced from 1972 to 1992 for sale in Japan by Subaru, although it was also sold in other countries, such as Chile. Recently it has become somewhat of a cult car in Japan, being used in front wheel drive drift events.

The Rex was the replacement for the Subaru R-2, which was meant to be the replacement for the long lived, but outdated Subaru 360. Because the R-2 was based largely on the 360, it lasted only a few years. In contrast, the 360 was produced for 11 years and the Rex was produced for 20.

The Subaru Rex, also known as Ace or SX700 in some countries, was a keicar automobile produced from 1972 to 1992 for sale in Japan by Subaru, although it was also sold in other countries, such as Chile.

The Subaru Rex represented a fresh start, having little do with the Subaru 360, although they did share a rear-engine layout. The Rex featured a 358 cc rear-mounted, watercooled, two-cylinder, four-stroke engine, upgraded from the two stroke engine used by the 360 and R-2 models. In 1981, the Subaru Rex became front wheel drive, and the engine was enlarged to 665 cc in 1982. The end for the Rex came in 1992, when it was replaced by the Vivio.