It is new software for your engine management computer. The knock retard on that particular management system is a little on the overactive side to say the least. After a relatively short period of time the timing will retard and or not advance to the point where your performance will drop off noticeably. We have customers that drop off for service and get a "new" loaner S40 for the day and come back asking why the loaner was so much faster/responsive than their car is/was. As a matter of fact we typically will disconnect the control unit on those cars when they are in for routine servicing just to reset the adaptive on them, brings the timing back to it's base setting among other things. I no the cost of fuel is through the roof but the more you use cheap gas the faster it adapts to the ping and the faster the performance goes out the window on it. So, spend the 40.00 and have the update done you will be glad you did.