they can mean different things. Redesigned front and rear bumper light assemblies. Body changed compared to earlier models to accommodate larger rear lamps, rear seat area modified to give room for new torque converter. Upwards folding rear spoiler and piston oil squirters in engine block on early cars only. Different horsepower rating for Australia due to different ignition map used because of possible low grade fuel. 1988 Model designation: 928 S4 / 928 CS / 928 SE (UK) Engine displacement: 5.0 L Valves: Four per cylinder Power: 320 PS (316 hp, 236 kW) (S4, CS and SE) / 300 PS (296 hp, 221 kW) (S4) for Australia Changes: Lighter 928 CS "Club Sport" version available in Continental Europe and USA, 928 SE (S4 Sport) in UK. Only model year for "CS" (USA) and "SE" (UK). "CS" uses different VIN sequence than normal "S4". Stronger torque tube with 3 mm thicker center shaft for automatic transmission. Pistons with strengthened skirt installed in February 1988. Oil drainage improved in piston skirts. 1989 Model designation: 928 S4 / 928 CS / 928 GT ("CS" model discontinued in USA) Engine displacement: 5.0 L Valves: Four per cylinder Power: 320 PS (316 hp, 235 kW) (S4 and CS) / 330 PS (326 hp, 243 kW) (GT) Changes: February 1989, manual transmission-only "928 GT" debuts as a better-equipped version (all markets). Digital trip computer/warning system added to dashboard, ignition circuit monitor system added. For Australian cars same ignition maps resulting the same horsepower rating as in other markets. North America manual transmission model now uses same shorter final drive ratio as used elsewhere, to simplify production. RDK tire pressure monitoring system optional on S4, standard on CS and GT. Thicker cylinder head casting taken into use early in model year to strengthen head against cracking. Longer head bolts needed because of the change. Modified front brake calipers with improved seals taken into use early in model year. 928 CS now had the same VIN sequence as 928 S4. Model dropped from production during the model year at the end of 1988. 1990 Model designation: 928 S4 / 928 GT Engine displacement: 5.0 L Valves: Four per cylinder Power: 320 PS (316 hp, 235 kW) (S4) / 330 PS (326 hp, 243 kW) (GT) Changes: GT pistons into use in S4 also resulting true 10.0:1 compression ratio for all engines. RDK tire pressure monitoring system standard on