Why does my acura tsx requiers premium unleaded gas? and the cadillac cts requieres any gas even regular?

The reason is technology. The Cadillac uses advanced technology to allow the engine to burn lower octane fuel without "knocking" or pre-ignition. The higher the octane of the fuel, the harder it is to ignite it. Using low octane fuel in a engine designed for higher octane fuel leads to pre-ignition, or the knocking, clattering sound you hear when the engine is under a load. Fuel and ignition timing, injector duration and pattern and engine internal design can allow a very powerful engine to still use "regular" fuel. Burning high octane fuel in an engine designed for low octane fuel is a waste and can actually damage the engine because all of the fuel may not burn and can dilute the lubrication properties of the oil. Burning low octane fuel in an engine designed for high octane fuel can cause severe damage to pistons, valves and cylinder heads.|||no, i think youre wrong. check the manual again and make sure to read what the car needs with watchful eyes. it should say Premium Octane Grade 93 or higher RECOMMENDED, and not required. the TSX is a four-banger and should run fine on regular (it shares the same exact 2.4-liter engine with the Accord which uses 87 regular). screw the caddy.|||it is not so much the compression, but the heat density of the engine will change the fuel requirements. the accura is a hotter running engine. more heat the greater chance of predetination. to control some of this you can use a higher octane fuel to eliminate some of the knocking.|||Acura Tsx has a high compression engine which requires 93 octane to run properly. caddy is not high compression so can use any grade of gas.