The fifth-generation Celica was introduced in September 1989 for the 1990 model year. The Celica received new Super Round organic styling, upgraded wheels and tires, more powerful GT-Four (All-Trac Turbo in the U.S.) with better cooling system, and for the Japanese market only, the four-wheel steering (4WS) models. Toyota engineers claimed that the round styling and lack of straight edges increased strength without adding weight. The Japanese market models were now S-R, Z-R, GT-R, Active Sports (first Toyota with Toyota Active Control Suspension), and GT-Four. The S-R and Z-R were powered by a 3S-FE engine, while the GT-R and Active Sports came with a 3S-GE. The 3S-GTE in the GT-Four features an air-to-air intercooler and CT26 twin entry turbo to eliminate exhaust gas interference. The Japanese market GT-Four has 165 kW (221 hp) and 304 N⋅m (224 lb⋅ft) of torque, a result of more aggressive ignition advance and ceramic turbine. The Full-time 4WD system in the GT-Four has viscous couplinglimited-slip center differential and Torsen rear differential.