Solved

Car 2 is always quicker in qualifying

What did you try to do?
Several Season, my 2nd car outqualified car 1 by a fair margin. I thought, it might just be a (hidden) driver attribute. But since my drivers are pretty similar, that seemed unlikely. At the beginning of the just ended season, I switched drivers position.
I expected car 1 would be quicker now, since now the "better qualifier" was in car 1.

What happened instead?
Nope! Car 2 is still quicker. Sometimes by several tenths of a second.

Did the problem happen while using wi-fi, mobile data, or both?
Both

Did the bug happen in the app, on PC, or both?
Both

What is the model of your device?
Doesn't matter.

What is the operating system?
Android

What is the version number of the operating system?
Wo cares!

What operating system is your PC?
Has nothing to do with my hardware / BS / software.

Which browser did you experience the problem in?
Come on, iGP, there got to be more irrelevant question! Try harder!

Can the bug be reproduced?
I did! A whole season of 17 races with switched seats. Drivers always demand same setup. Treated them equally regarding repair/engines and quali tyrtes (most of the time).

Additional comments:
Most recent season. Car 1 Turner; Car 2 Jackson
02Aug CN Car 2 by 0.13
01Aug CA Car 2 by 0.18
31Jul EU Car 2 by 0.39
30Jul RU Car 2 by 0.08
29Jul BR Car 1 by 0.06 *Heavy Rain, wrong tyres (I)
28Jul GER Car 2 by 0.05
27Jul HUN Car 2 by 0.12
26Jul FR Car 2 by 0.16
25Jul AUT Car 2 by 0.07
24Jul BAH Car 2 by 0.17
23Jul ESP Car 2 by 0.02 * both unrepaired, unattended
22Jul GB Car 2 by 0.11
21Jul ABD Car 2 by 0.06 * both unrepaired, unattended
20Jul MAL Car 2 by 0.54
19Jul AZE Car 2 by 0.10 * both unrepaired, unattended
18Jul BEL Car 2 by 0.39 * both unrepaired, unattended
17Jul AUS Car 2 by 0.09

=== Switched driver 1 <=> 2 at this point ===
Car 1 Jackson; Car 2 Turner
15Jul ABD Car 2 by 0.14
14Jul SIN Car 2 by 0.04
13Jul MAL Car 2 by 0.04
12Jul CN Car 2 by 0.12
11Jul CAN Car 2 by 0.00
10Jul EUR different tyres, sorry!
09Jul JAP Car 2 by 0.05 * rain
08Jul ITA Car 2 by 0.19
07Jul BRA Car 2 by 0.10
06Jul HUN different tyres, sorry!
05Jul ESP Car 2 by 0.09
04Jul GER Car 2 by 0.10 * both unrepaired, unattended
03Jul AUS different tyres, sorry!
02Jul FRA Car 2 by 0.18
01Jul BEL Car 2 by 0.06 * rain
30Jun BAH Car 2 by 0.20
29Jul Mon Car2 by 0.20 

I drove with Car 1 Jackson; Car 2 Turner several more seasons previously. But I guess, these 2 seasons paint the picture pretty well.

Edit:  Links to races added.

Wow, that is either a mega fluke or I want to see their code.

I have the same issue for a few months now

they want to see the games code too, no way have they seen it and still produce so many bugs.

under fuelling, not putting on correct tyres during stops, its all there just denied.

Be careful guys! This can go either way. Of course, I hope my car 1 is too slow. But at the same time it can be car 2 going faster than it should be!

Either way, to me it is clearly a bug. Unclear if I am suffering or gaining from it.

The same...I was using two almost identical drivers to have the same time in quali. And it was right until a day where everything changed...Then I started testing...

These were the race where the two drivers Hosokawa and Nara had everything identical.
China
Mexico
Russia
Europe
Turkey
Spain
Abu Dhabi

I had that: Everything the same, tyre, health, setup and repaired car -> same time....then, since Australia Gp probably...the end, Hosokawa started qualifying always behind Nara, that was the second driver.
Australia
China
Hungary
Singapore
Monaco
Bahrain
gb
usa
Belgium (+0.372!!)
France

The championship ends..the following season (the one I'm playing now) I started swapping driver number 1 and 2. Unfortunately, I have 3 drivers and I cannot choose Nara as first and Hosokawa as second. Anyway, all the quali results that I'm going to show: 2nd driver qualifies first and the first driver had a worse tlaptime, ALWAYS. (I used all three drivers)
Australia
Malaysia
China
Turkey 
Monaco
Baku
Canada
Austria
Hungary
gb
Spain
Belgium (+0.655!!!!!!!!!!!!!!!!!!!!!!!!)
Italy
Singapore
Russia

No exceptions, never, since the Australian Gp that I put first in the list. Note that I can create both the couples Fakuda-Nara and Nara-Fakuda. This is why sometimes Fakuda is first and sometimes Nara is first. But I can assure you that it is always the second driver ahead with both drivers in the same conditions. 

Same thing here; we know that normally the tallest drivers have the best quali results. 
But trying to play in a 2-cars league my 2nd car is always the best in terms of quali lap, even with a 158cm driver vs a 192 one. 
I'll post something. 

EDIT:
Azerbaijan 2nd driver 
Mexico 1st driver, only exception
Russia 2nd driver
Italia 2nd driver
Singapore 2nd driver
Malaysia 2nd driver
Belgium 2nd driver
France 2nd driver
China 2nd driver
Austria 2nd driver
Australia 2nd driver(*)
Bahrain 2nd driver(*)
Germany 2nd driver(*)
Spain 2nd driver
Japan 2nd driver
Abu Dhabi 2nd driver
Hungary 2nd driver
Brazil 2nd driver
Monaco 2nd driver
Great Britain 19 2nd driver
Canada 2nd driver
United States 2nd driver

In the races with (*) I swapped the two drivers to see if anything would have changed. 2nd driver faster again.

I have had the same issue for what must be an entire year now. My second car is quicker than my first, this is the case on both of my level 20 accounts. The only time it flips is in wet races it seems.
It's very clear that there is a hard-coded difference between the first and second car. Why? I don't know

Hello Managers

I thank you for all the precious data.
I have collected the data and I will write a report for the devs. I leave the thread open for future updates.

Do you know when? It's a very unfair situation and it's a very serious handicap for people playing with 2 cars. For people that can have close drivers it's really easier to manage the race. 

Yes, I am in very competitive league myself. Joining the races, I always joke that I got the biggest gap, place-wise, between my cars. Sometimes more than 10 spots. That's really annoying strategy wise. Even the on screen handling (keeping DRS distance, etc.) is tough, if one car is in top5 and the other in midfield. I wouldn't complain, if this were common to all managers. But my opponents have their cars right next to each other, while mine are miles apart at times.

Hello
To date, I don't know the exact date. What I can tell you is that I have forwarded all the data posted here in the thread.

In my other account, all season long my second driver pipped my first driver in qualifying. However all of a sudden, today he was about 7 places back from my first driver, which hurt my race. Was a change implemented? Or are driver errors a think again? I know it’s close in qualifying there, but very unusual.

The devs are aware of the problem!

this has been going on for years and only now they are aware, wow, no wonder pit stops are still broken it takes them years to be told things,lol.

It is getting worse:
1st race of new season: car 2 by 0.26s => 13 spots in grid
2nd race of new season: car 2 by 0.37s => 18 spots in grid

I am thinking about retiring car 1, i.e. won't repair anymore. Or quitting the game for good.

"this has been going on for years and only now they are aware, wow, no wonder pit stops are still broken it takes them years to be told things,lol."
I have played this game since mid 2016, not one player has reported this problem in these forums since. The first step of solving a problem is knowing there is one in the first place mate.

Well, variance in qualifying has been removed recently. Up until that point, it was difficult to pin-point the problem, since variance was on average greater than the differences between the two cars. It would take lots of data to see such a small systematic error.  

Drivers (i.e. car 1 and 2) don't have to be equal pace in quali or race. But my point ist this: all other managers in my tier have their cars close to each other. I don't. And there is no obvious explanation like driver skills.

If every where to use same tyre type in quali, I might end up being first and last!

could it be that some drivers don't like racing in car 1? I have been messing around with some and seem to have found 1 that can get pretty close to my no.2 driver