PD NEEDS to implement qualifying and here's why.
The game encourages you to pick a car that will blow away the competition. Why? Because you start in last place for each race, and have only 3 to 5 laps to make your way all the way to the front. If you try and pick a car that's comparable to the AI competition, you would never make up this many positions in such a short amount of time.
So what's the solution now? Well you pick a car that you THINK is going to make up 12 positions in 3 laps for example, so it's gotta be faster than the AI - but not too fast or it will be a boring time trial by the last lap. Not too slow though, either. So really you're just guessing to pick the right car with the right tuning that will put you in the hunt for first in the last corner.
In the future, if PD would implement a qualifying system (and standing starts please!), then you could run a couple laps to see what time's the AI are posting and pick a suitable opponent with similar PP in which you'll have similar lap times.
In my opinion, this would vastly improve the offline racing.
I've also hear people asking for an AI slider like Prologue had - while that might be a nice addition, it's not going to solve the problem I stated. Starting last in every race, with a few short laps to make your way to first, ENCOURAGES lopsided and unrealistic racing.