Basically different redline textures for the tachometers depending on the trim level. So for example, the Sunburst's tachometer has a redline of 6,500 RPM, but only the base 1.8 model has this redline. The sportier models and the racing models have redlines of 7,000-7,500 RPM. So maybe a separate tachometer gauge that has the redline changed to match? Or like how the Gavril D-Series and Roamer tachometers have a redline of 5,000 RPM even though almost none of the engines have that redline? The inline 6s and V8s all have more than 5,000 RPM for their redlines, so increasing this would make sense. Or one with a much shorter redline for the diesel engines. The 200BX has a 6,500 RPM redline but the LS version has a slightly longer one, so a tachometer to match could be a little attention to detail. TL;DR Variants of dashboard tachometers with redlines textured to different RPMs to match the engine redlines depending on trim levels. Of course this doesn't have to apply to every vehicle, just the major ones where it'd make sense (such as the Sunburst or the D-Series/Roamer).
