The AI is very fast on the straights

Without seeing gameplay or knowing exact situation like track, setup, car and difficulty it's very hard to comment exactly but what I can say are 3 big things that myself and many others HAVE found with this game so far.

1) the drs is mentally strong this game and coupled with NO dirty air it's borderline broken. That coupled with the AI abusing ERS whenever they get a sniff of an overtake can make them seem like rockets.

2) The AI still don't fully utilise track limits and stuff like players do so we often make up time in certain corners but lose out on the straight because in order to balance the AI difficulty with us taking that advantage we turn the difficulty up and it makes the AI better than us in other areas like traction onto big straights in order to balance out the overall lap time. I strongly suggest forcing yourself to drive track limits closer to reality like the AI do when playing solo and you'll realise jow much you were gaining on them. It's very hard to do all the time though when you know the free time is sitting just over that curb or line lol.

3) and this is the biggest one, the AI speed in quali to race are unbalanced completely the other way around to last game, but much worse than before! Watch anyone playing single player online at the higher levels and ALL of them are commenting that the AI are so fast in the races.

If you're qualifying around 105, which funnily enough I'm doing now as well, I'd strongly suggest you knock the race setting down to under 100. If you haven't got a custom setup on, especially a TT one which will ALWAYS be better over 1 lap, you'll find this brings the AI pace somewhere closing to yours in the race relative to what it was in quali. For example, I've just done Imola and monaco on myteam S1. Qualified on 104 and 105 in a bottom tier car, top 10 at imola and top 5 at monaco. I raced on 97 and 98 and every car that I obliterated in quali was still lapping faster than me. And that's with the suggested setup which you would think wouldn't be too far off what the AI are using and should be fairly well balanced quali to race. 

I suggest to test you go do a quick short GP mode race on a fairly balanced track, so not monaco or Monza, and do short quali driving as someone that has a fairly high rated teammate in the same car, Mclaren with Lando as teammate for example. Use the suggested setup with only minor parc ferme allowed tweaks for personal preference. I myself add couple clicks front wing, knock brakes back to about 59 and maybe take 5% off the on throttle diff, but that's it. Do quali without taking the mick with the track limits, or doing "right on the edge" laps that you can't replicate, until you find an AI setting that has you roughly around your teammate in pace. Once you find that number, knock it down by about 7 or 8 and start the race. Use the race director to see what tyre your teammate is starting on and copy it. Do your best in the race start to stay around your teammate so you can see each others pace in same conditions. So no abusing a faster cars DRS train if teammate doesn't have it as well for example lol. See if laps times are similar and adjust difficulty accordingly. 

Through this test at Melbourne the other week, when I hadn't spent much time on the game yet, I found I could comfortably qualify around Lando on about 104. Sometimes I'd be faster, sometimes he would, depending on what lap time he ended up doing as there is some degree of randomness. 105 was possible but I had to nail really good lap and push the track limits above what the AI will do, while still being legal of course.

When racing I had to go all the way down to about 96 or 97, otherwise Lando would get in front and I'd be clinging onto him using DRS but getting overtaken easily within a few laps If I decided to pass and try to pull away. Or If I had DRS to faster cars ahead I could outrun him but again that's an unfair comparison given the OP power of DRS on this game.

Let us know how you get on.

My test is on twitch if u decide u wanna watch yourself.