Talk:FERRARI F50/@comment-71.176.209.188-20150512202932/@comment-208.184.33.66-20150512204429

It is not an error. It is a reflection of how the PR numbers are not 100% precise. By that I mean, they can have a different impact on the car's PR rating depending on what other upgrades you already have. I suspect the reason is that they are calculated by the game to a further decimal place but not shown to that degree of specificity, so when you have already done an upgrade that, let's say, is given .84 of credit behind the scenes and are looking at another upgrade that has .84 of credit, the game will show that the marginal increase if you buy that upgrade will be .9 because the game will round up the 1.68 of PR increase (based on these hypothetical numbers).

This imprecision led to the (hotly contested) decision not to include the PR numbers in newer pages about cars (instead there is a separate page for this information). While it is important to keep this imprecision in mind when making upgrade decisions, once you realize that the numbers are rounded to one place and are, therefore, potentiall .04 off, it becomes easy enough to account for.