Compensation for changing shifts
If there was no agreement at the time to reimburse your member for the cost of buying or running a car, or any other agreement as to additional transport costs, there is no legal obligation on the employer to pay these costs.
Although the change in hours was eventually imposed rather than agreed, the fact that your members have worked the new shift system for a year without challenge is likely to mean they have acquiesced to the new terms, meaning there is no breach of contract.
Even if that were not the case and you had an argument for breach of contract, that wouldn’t help with the cost of the car since that wasn’t a term of the original contract.