The DVLA is closing 39 regional offices before the end of 2013 in order to centralise operations at its Swansea headquarters.
Retail Motor Industry director Sue Robinson said the proposed changes would mean dealers would have to adapt their IT systems and infrastructure.
Robinson said: “Currently there are 80 different transactions that our members carry out relating to vehicle tax and registration.
“Of those transactions, 12 of them have to be carried out in a local DVLA office. This is a requirement set by law.
“We urge the DVLA to ensure that new regulations and infrastructure are put in place before the proposed closes to ensure our members can continue to run smoothly and within the law.”
The Government has said it could save £28 million a year by closing the DVLA offices. It hopes to increase the amount of DVLA transactions online as a result. Unions have described the closures as “devasting”.