Perfect advise as always guys.
I've had a similar situation with a previous company many moons ago, and i refused to drive it as eventually the metal was poking out of 3 of the four tyres.
I was sacked via some c o c k & b u l l story about poor workmanship !!!!
So, enter a free company called ' Step one ' who fought my case FOC at tribunal and guess who won .....
Do not be bullied by a company/ an employer. You have rights, if not more so.
Best of british - but i would urge you to act swiftly if the vehicle is indeed as you say as i would niether like to see you A: dead / injured or B: disqualified.
Good luck friend
Eddie