From the Motability website - latest Covid-19 Update:

With less traffic on the roads as a result of the lockdown, will I be eligible for a refund from my Scheme insurance?

Yes, as lockdown has led to fewer drivers on the road, the Scheme is seeing a lower level of claims, enabling it to share a windfall with customers. We have made this decision in consultation with Motability, the Charity. As a result, we are set to send an insurance-based refund of 50 to every car and Wheelchair Accessible Vehicle customer.

There is no need for customers to contact us in connection with this insurance refund, as we will automatically issue this payment as soon as possible from the second half of May.