Carmakers are under pressure to drum up £3bn to cover payouts for motor finance scandal victims after failing to adequately prepare for a UK-wide compensation scheme that is due to begin this summer.

Company filings show the lending arms of big vehicle manufacturers including Ford, BMW, Stellantis and Volkswagen may have massively underestimated the final costs of the financial regulator’s £9.1bn redress scheme.

The Financial Conduct Authority (FCA), which released the final terms of its compensation plan last month, has said about 42%, or £3.8bn, of the total bill will be shouldered by carmakers’ motor financing divisions.

However, manufacturers have collectively put aside just £803m. They will have to scramble to put together a further £3bn needed to cover the bill, which will help compensate drivers who were mis-sold car loans between 2007 and 2024.

The compensation scheme is intended to draw a line under the scandal, in which drivers were overcharged for vehicle loans as a result of commission payments between lenders and car dealers. The FCA has estimated that victims will be in line for payouts worth £830 on average.

Lenders embroiled in the scandal have heavily lobbied regulators and government officials over the past two years, saying that large compensation payouts could force some providers to withdraw loans or even collapse.

Carmakers’ involvement has turned up the political heat, with ministers wanting to ensure manufacturers are not deterred from investing and creating jobs in the UK.

Anxieties over the potential fallout from a compensation scheme – which at one point was expected to come with a £44bn bill – led to a string of controversial interventions, including the chancellor, Rachel Reeves, urging the supreme court against awarding large payouts last year. Last summer, she also considered overruling the court if it sided too closely with consumers.

Of the £9.1bn compensation scheme, roughly £7.5bn will go to customers in the form of redress payouts, while the rest will cover administrative costs including contacting victims, making payments and other general running expenses.

Lenders not tied to carmakers – including high street banks such as Lloyds, Santander and Barclays – are on the hook for 57% of the total bill.

But unlike car manufacturers, they are much more prepared, having already put aside £3.9bn of the £5.2bn bill they are likely to face.

Of the carmakers, Mercedes-Benz has put aside the largest sum to date, totalling £424m, followed by BMW at £207m, Renault at £74m, Ford at £61m and Stellantis at £37m. Toyota has indicated it has put aside money for the scandal without stipulating the figure, while Volkswagen and Ferrari appear to have not put aside any funds to cover compensation to date.

Benjamin Toms, an analyst at the investment bank RBC Capital Markets whose team compiled the lenders’ provisions, said: “There are probably three reasons why UK banks have been more proactive in their provisioning.

“Firstly, because this issue was more material for them. Secondly, UK banks will place a high level of importance on their relationship with the regulator, and thirdly, finance goes more to the heart of banks day-to-day operations relative to car manufacturers where finance is a side arm.”

Lenders and consumer groups still have until 5pm on 27 April to challenge the FCA’s scheme and its proposed compensation bill, a move that could end up significantly delaying payouts.

The FCA declined to comment on the carmaker’s compensation bill shortfall.

A spokesperson for Mercedes-Benz said: “We are not in a position to comment further as we are still reviewing the findings.”

BMW said it started putting aside money for the compensation scheme before the FCA finalised its compensation scheme, “in line with applicable accounting standards and based on the information available at the time”.

Ferrari said the estimated financial impact at this stage was “not material” given that the FCA had excluded claims for high-value loans “higher than than 99.5% of other loans that year” such as those needed to buy its sports cars, adding that it would provide updates in due course.

Volkswagen Financial Services UK said it was “carefully reviewing the detail to understand what it means for our business and our customers” and would continue to engage with the FCA to ensure the process remained fair and proportionate.

Renault welcomed the clarity provided by the FCA and said it would provide further updates.

Toyota declined to comment. Ford and Stellantis did not respond to a request for comment.