I see a negative dynamic response on my cars all the time, and I’d like to know what’s causing it, or what dynamic response even is, and what’s it based on, because it’s puzzling me 
It’s rating saying how a car responds to steering input, i.e. it’s good if it’s agile and spory and bad if the car is very sluggish or nervous. But in the current public build this rating is pretty unbalanced because I didn’t have mid-engined cars for balancing at that time. So don’t pay too much attention on that yet. The dependencies are pretty complicated and it’s difficult to improve only that stat without changing the car overall (interior, drivetrain, tyres, weight distribution, …). It’s more a result of all the major choices and is needed to give the mid-engined cars the extra sportiness they deserve.
Ah, that makes sense. Also, thanks for the info 
What would you say a decent score for it is as-is?
Everything around 0% is fine. It goes up to +5% I believe.