The vehicle section is not complete at this point in time per TurboTax. It says it should be ready by early February or sooner
Was it covered by insurance and if so, did you file a claim? The IRS denies losses when insurance is available but not claimed You can also take a deduction if there was no insurance or claim denied
The issue with TurboTax right now is that there seems to be no way to indicate it was removed from service due to a casualty. This could result in you inadvertently taking a loss on it twice. Once on form 4797 because of entries on the vehicle worksheet and again on form 4684. This may be fixed once the vehicle worksheet is updated
If you do not have good records as to business and personal usage or this was a personal vehicle converted to business use , there could be additional issues.
