i know a couple cheap improvements that work excellent for my 425 but everybody knows this..a brand new air filter,oil change,belts,oil filter,i know this works great for a fact cause i live in phoenix and i go up north quite a bit and one time a drove up north without no oil change,new airfilter,oil filter and i top'd my car off and when i got to my destination(1hour 45 min away) my caddy was already out off gas ...just on the way up their...then this christmas i went up north again got everything done and i still had 3/4 tank their and back...treat your car good and it will treat you good..thats for sure
