When i bougt the game like 3 weeks back i was trying to get my friends to play MP with me in the build where it works, they did for a brief time but ultimatly said "na i want to play the new stuff, we wait for b41 MP, ANYHOW ....cars worked for us in that build, i didnt experienced any issues but maybe that was just to short of a time to run into issues idk.
What i can say at least is that i seen that kinda flipping around in other games before and to my knowledge all those kinda "bugs" happen when things end up occupieing the same place and the programm is trying to sort it out.... thats its solution for the problem just move the objects away from eachother, my guess is that this is happening when things are HERE for you and THERE for me then suddenly there is a zombie under my wheele without me physicaly properly running him over, programm just "beamed" it there, cars conclusion: need to correct position upwards.
Could be something entirely different but IF this is the case here then it could be as simple as turning off collisions car->car car->player and car->questionable zombie, like if its "mine" and i run it over yes die but collision off for other cars with those zombies till they have a final resting point and maybe some tweaking how z´s agro cars cause car/player A having agro and losing it to player/car B probably resulting in zombie sync "masking" warp probably happen here as well right?^^
This is just a wild guess but one coming from a guy with an education as software developer who never worked the job commercialy and chose a literal lifetime of gaming instead with 38y old now, so maybe worth looking at
To be fair its probably not gonna be exactly that but my guts telling me this is going the right direction and you may find some inspiration from that, so i hope this could help and we see MP soon, fingers crossed you find the issue before holiday periode,
GL fixing and Peace OUT