Since a few years now F1 drivers are allowed to choose their car number.
Numbers from 1 to 99 (Antonio Giovinazzi) are available - in GP2 only numbers from 0 to 40.
There was such a big development for GP2 in the past and I can't believe that this problem isn't solved yet...
Is it a big deal to patch the game to have the actual car numbers?
Yes, the game uses the car numbers for looking up various tables and it is quite a challenge to get them changed outside the original range without breaking it. It should be something GP2Lap could theoretically do but it isn't developed any more. We would need someone with advanced knowledge on both C and Asm to add such a feature.
"The Fox provides for himself. but God provides for the Lion"
Early 90s F1 forever!