Consumer champion and Budget Road Revivals presenter Martin Lewis has launched a free tool for consumers to use in logging a complaint about discretionary commission agreements (DCAs) in their car loans.

The star mentioned in the latest episode of the hit Netflix show that he's watching the FCA's review of historic DCAs closely, urging young drivers to pay attention to the small print of motoring developments.

The FCA launched its review after the Financial Ombudsman Service ruled in two cases that lenders' DCAs, combined with a lack of full disclosure to the customer, had put car buyers at a disadvantage and were unfair. The FCA's review hopes to quickly determine if this is a widespread issue.

"My view on this is I don’t believe it would have launched this investigation unless it already had substantial evidence and the likelihood is the investigation now is to make sure it’s got everything right so it can’t be judicial reviewed," said Lewis in his halftime segment.

"I think it is very, very likely it is going to rule that there was seismic, systemic mis-selling."

Lewis added: "A back-of-the-envelope calculation shows this will likely end up being the second biggest ever UK reclaim campaign, after PPI. The average payback will likely be over a grand."

Lewis wants to discourage people from going to claims management companies, which would eat into any compensation that might be awarded.

"I think it likely that, when the investigation completes (currently planned to be September), the FCA will set up some type of mass-scale redress scheme – though there's a small chance it'll change its mind and say this is a damp squib. The best way to act is to assume that scheme is coming. 

Lewis urged consumers to take action quickly, which has led motor finance firms and their regulated broker and dealer partners to expect a flood of complaints in the coming weeks.

The FCA recently said it has gone into the review with no prior assumption of what it will find.  

The investigation is ongoing.