Combining multiple cells into one (without losing data) if the rest of the row is equal

Got it.

Here to regroup the years, i have used a simple if formula in sheet "Blad1", A1

=IF(OR(B2=1990,B2<1993),"1990-1992","")

Post how you want to regroup the years, we can modify the formula and get a list per the need. We can proceed from there.

OK let me just add an excerpt from the actual file to make it more clear. The formula you mentioned would still require some kind of manual input of the years because in the example it only had 1990, 1991 and 1992 in it. But in reality some cars are only made in the 80's while other ones are from the new millenium etc. So with this formula I would need to look up per car the lowest and highest year it was made in and enter that into a formula. That would still be a huge task.

Attached a piece of the original file I am working with:
car_applications_actuallist.xlsx