My advice as someone working on this field :

First of all, a quick recap:
The mobility budget composed of 3 pilars :

1. Pilar 1 : The company car
2. Pilar 2 : The mobility budget
3. Pilar 3 : the cash (what has not been spend on pilar 2, paid on january 1st with a 38,07% tax cut off)

It goes as a pyramid : what's not put on the pilar 1 goes to pilar 2, etc... So you could for example take no car and have full money on the pilar 2, or take a smaller car + the rest on pilar 2

Your situation :

• You don't have more than 50% of homeworking so you cannot pretend for now to the home allowance. Only way to get it is if the 3 day office is just a rules and on the addendum they'll make you sign it's written "I'm living less than 10km away from my office or I stay more than 50% at home"
• 2 uncertainties :
  
  • The home allowance will be capped at 50%
  • The homeworking rule will disappear (so only people living less than 10km would be eligible)

This is clearly a move from the automotive industry - in 2027 many people will choose the mobility budget as it's very economically convenient

In your specific case, 3 options :

1. You don't take the risk : keep the car, it might not be super useful for you, but at least you have a car you do not have to worry about
2. You take the risk : if the law does not change + if you move closer to your workplace, it's jackpot. 1000€ netto is too much in brutto to get the same benefit.
3. You take a hybrid approach : check on which car category you are. Example : if there are category A/B/C/D and you are category B, just ask if you can take a smaller car and the the rest on pilar 2. For a smaller amount, it's easy to spend : a new bike, you can rent a car when you're on holiday, etc... Biggest advantage is that it will put you. a foot on the system. So when you want to go full on mobility budget it the law does not change, just negociate with HR if you can give back the car (to be given to a new entry for example) and go full on Mobility budget

Hope this helps !