hello ..to awnser your question: the fe1 is the base suspension=soft ride you get the 17x8.5 front wheels and 17x9.5 rear wheels smaller stabilizer bars softer billstein shocks the f45 is the electronically adjustable suspension wich adjusts itself depending in road condition softer to firm via sensor in each corner of the suspension of the car..the z51 suspension wast the h.d. one wich has stiffer leaf springs h.d. billstein shocks 17x9.5 wheels in all corners bigger stabilizer bars in fron and back..if u want something rare try getting a collector edition with the red interior and lt4 and suspension wise oi guess its up to you depending on how firm or soft u want your ride 2 be..