Suggested

No setup - no race

In the elite divisions, there is a rather serious problem of lapped cars, because their DRS can greatly change the results of the race. And also now devs are starting to attack the farm accounts, which comsuming his tokens, and don't set up their cars, because that's not necessary...
I've got an idea here. It doesn't happen often in my hand.
What do you think about not allowing cars without setup to race?
Devs set some condition in the game, if you don't fulfill it, you are not allowed to race.
For example:
1) (1 lap in practice OR perfect settings) And a changed strategy
2) Lap time in qualifying is less than 102% of the leader's time OR ((1 lap in practice OR ideal settings) And the lap time in qualifying is less than 105% of the leader's time)
Of course, in this case, it will be necessary to change the rule for moving to a higher category (remove the condition that 16 managers must have at least 1 race at the league), and also not to introduce this rule for Rookies. Otherwise they will be surprised when they see only themselves in the race.

If you want to have many players with own strategies or perfect setups, there is the possibility to give them points too. 1 point for perfect setup and minus points for each lap behind. All players with minus at the end of the season go down from elite to profi.
Next possibility.
That's the chance for profi because if 7 elite have to go down, 7 profi have to go up. Or are making a qualification race for up or down at the end of a season.

To your souggestion.
What's about the financial if they don't race?
Get no bonus but have to pay wages?
Do they loose a motor and spare parts, if they don't take part?
No race = no experience points for the driver and staff?
No race = no development points for the next race and next season? 

In Formula 1, there are no points for setup the car) Why any more points when the offer is simple: no setup - no race. And no lapped cars in race! 
And your addition is very good:
No race = no bonus for the race, but you need to pay to the staff. Or half of the bonus if one driver participated in the race (in leagues for two cars).
No race = no experience points for the driver and staff. If only one car participated in the race (in league for two cars), the driver gets full points, the staff gets only half of the points.
No race = no development points for the next race and the next season. Or half of the points if only one driver participated in the race (in league for two cars).
But the engine and spare parts aren't consumed if the team didn't participate in the race.

i agree with this one.
Managers not caring should be punished actually.
this would also fix the afk token farm managers by itself.

i think it is possible to see if there were setupchanges made and the strategy is done for the race.
even if he is afk then he get punished by the ppls playing live.

The problem goes a bit into the dark side when inactive elite guys getting demoted grand a hugh amount of xp for the races what is not ideal for other drivers.
It is hard to stay updated with your HQ and if you level that quick its even harder.

So no exp, no money and no tokens for afk guys is the best solution for every active driver imho

You must not forget that every so often, for "reasons", peoples lives catch up with them and they just cannot setup if the wanted for a while.  I would say, also, that although, very annoying for some, or many, the backmarker problem in races adds to the tactical complexity of the game.  So, some backmarker activity would be interesting, overall.  But not as much as we have now.
So, my add on to this idea, would be to have a no setup, no race rule that kicks in, either, 2 races after suspension retirements start, or, after n days of inactivity, overall.  In the second case, n should either be 7 or 14 days (I would go for 7) to allow for those active people taking well deserved holidays in places of no mobile/cell reception.

good point, there.
So yeah. Give them 7 days or so sounds fair.
it still would help to get rid of inactive accounts which lasts for ever in beginner league then.
Better approach imo is to add a vacation flag for the account which can only be set like once in three month or so, so it cant be abused that hard.
And then after 2 to 3 days inactivity stop them from racing.
The approach with 2 to 3 days after damage is also a good one but for me actually to late.

It could be a mix of both.

After n days without setup ( n could be choose by league host) : No setup - no race.
Meaning no point, no xp gain, no reward of any sort but you still have to pay for the wages. (No parts or engine used as if the team didn't even showed up for a whole race)

And you could use your "vacation flag" to show everyone you will not participate in the next few races. It would mean that you still don't get any reward but you don't have to pay the wages and you still get the design point for the next season.

Juste like a place holder in your current league for when you get back to the game. 

I would not add a limit to this though. Every league manager is then free to deal with different behavior as they wish. (let's say there is people using this flag every weekend but it's no big deal with the league. Why punish this?)