Car keeps falling through map

Hi all,
Been a while since I've been here. (Was the one that ported Driver 2's Chicago whilst painstakingly fixing god knows how many holes in the buildings whilst replacing anything upto 400+ trees with 3D ones).

I've recently gotten my hands on all of Driver 1s levels in OBJ and VRML file formats. I've been trying to do a test port of Newcastle and although it shows up fine ingame, I cannot get the collisions to work at all.

I've tried:
1) Matching the orientation of the map to an object with known working collisions
2) Making a collision model (shows up as purple wireframe and matches in shape editor but car still falls through it.
3) Checked the normals and they appear to be ok (blue facing upwards in similar manner to known good working one)
4) Have tried all the different collision modes that BeamNG offers.

I know when I first started a couple of years ago, I had the same problem but eventually worked my way around it. I've been at this for the past couple of hours and have gotten nowhere with it. Is there anyone that can have a look at my files to let me know what I'm doing wrong please. If I can be shown what's going wrong, I'd like to try my hand at porting the remaining cities across in due course. Driver 1's cities would require virtually no fixing as they don't suffer from the missing geometry issue that plagued the fronts of Driver 2's buildings.

Source files:
https://mega.nz/file/YMsVkC4A#CRju4bPaB3epw6lpN2z0xhj6zfpSIvvDWr-rQuSZSOo

Renders:
https://i.imgur.com/15uPjY7.jpg
https://i.imgur.com/EKwPkyP.jpg
https://i.imgur.com/GBGizSn.jpg
https://i.imgur.com/S53VtMG.jpg