Heh, I am starting on my second pass. This will take much more time in that now is when I will be exploring my garage and various tunes. In the first pass I just grabbed a car and went - in most cases completing the entire class with a single car.
Exploring my Garage entails building out my Top 10 best cars for each class. This can not help but involve some of the scoreboard cars. However, consider this... Scoreboard Cars also sport a Scoreboard Tune. Most of the time this tune renders the car unsuitable for anything but running hotlaps on that specific track. In that I do not, and will not, run a Toon like that - I don't consider the fact that the make/model is in my garage means that I am running a "Scoreboard Car"
If a car makes it on my Top 10 list it will be because of it's QR with a single Toon. Then the car is
Tranked (That is a new word - I just made it up. A car that has been "Tranked" has been run on all nine track ranking tracks.) Once tranked, the car is then pitted against the tracks on which it appears to be best suited.
If when it is all done, I wind up with a time using a "Scoreboard Car", then so be it.
As for the activity. The building, testing, practise, rinse and repeat nature of this activity is what captures me about this game. In my mind, it is the ability to do that, that is the most "Sim-Like" property of the game. Think about it - what do you think Jeff Gordon is doing right now? You betcha... same damned thing only in a real car.

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