I am considering the purchase of one of two E28 cars. The first is a beautiful 1986 535i that looks like a new car (well this is a stretch) or a 1988 535is that looks great but not as beautiful or well taken car of as the 535i. My question to you is do you know the difference between a 1986 535i and a 1988 535is? Do you know how to determine the value of each of these cars and is there a substantial value and collector difference between the two? I thank you for your response ahead of time. I am sending this out to a few E28 owners. I have owned BMWs exclusively for the past 26 years. I love the E28 and have owned several.