As in acceleration the 3.5 aurora looks as if it can beat every 95-99 aurora from what I see on youtube, then it seems that the 01-03 aurora 4.0 is the fastest. And the 3.5 aurora's get more mpg and has less wieght and is barely slower than the V-8 2nd gen. Roads test says its better balanced and handles corners easier but the last thing is the options what does the 3.5 aurora not have that a 4.0 does. One I know for sure is the nice chrome 17x7.5 wheels. So what is the best aurora if thier ain't one then why not go for a 98-03 seville sts blk/blk chrome and call it done you can find some around the price. This is just for a nice used midsize car and not much in aftermarket performance parts and rear drive edge. But looks to me the 3.5 aurora or get it done right sts and same V-8 mpg.