Hmm, where's a mod when you need one? This discussion really didn't need to turn into an argument. In real life, different cars read speed differently, which may mean some cars will display 100mph (for example) while wheelspinning at a standstill, where some won't. Of course I don't think this crossed PD's collective mind, but whatever. This feature would be totally useless to me, I barely ever look at the speedo unless I'm working out gearing or doing the start-stop license tests, however some people might find it useful.
At the end of the day, need it or don't need it, it's not in the game. I suggest you learn how fast your car goes at certain in-gear engine speeds and guesstimate your wheels' actual speed going off the revs it's doing while in a slide, because there are other, more pressing, issues for PD to fix, whatever they may be.
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