Money guru Martin Lewis has sounded the alarm for drivers over potential car finance misselling payouts that could reach a staggering £15billion. The Money Saving Expert chief rushed to his Twitter feed to deliver his immediate thoughts on the Supreme Court's landmark ruling regarding the car finance misselling controversy, which may result in millions of motorists receiving billions in compensation for allegedly dodgy car finance deals. Britain's top court determined on Friday that car dealers weren't bound by a relationship with their customers that would demand they act "altruistically" in the customers' interest. A ruling last October established that three motorists, who all purchased their vehicles before 2021, deserved compensation after being kept in the dark - either inadequately informed or not told at all - that car dealers, operating as credit brokers, would pocket commission from lenders for bringing them business. On Friday, judges concluded that car dealers weren't tied to a relationship with their customers requiring them to act solely in the customers' interest, declaring the Court of Appeal had got it wrong, reports the Express . However, they noted that some customers might still secure payouts by pursuing claims under the Consumer Credit Act (CCA). Just one of the three motorists' cases received the court's backing as 'unfair' regarding the relationship with the finance company. Martin Lewis issued a stark warning to motorists that in the wake of Friday's court ruling, they must steer clear of claims companies as they risk losing up to a quarter of any compensation. Martin explained there are two distinct types of car finance mis-selling scandals. The first involves discretionary commission arrangements - essentially PCP deals or hire purchase agreements arranged through brokers or dealers before January 2021. Your interest rate may have been bumped up from the bare minimum so your broker or dealer could pocket extra commission, Martin revealed. Martin noted: "That was banned in 2021. What could have happened last year, the regulator announced it would be investigating that and it is very likely people were missold on that basis, is what we're thinking right now." He continued: "What we were waiting for in the Supreme Court decision was if it said anything that stopped Discretionary Commission Arrangements being done, or a redress scheme being done by the regulator. There wasn't anything as far as I can see right now. So I suspect within the next 6 weeks, it will launch a consultation for a redress scheme." Martin then delivered a 'very big warning': "There's a possibility that redress scheme may be automatic, in other words you don't even need to put a claim in and you'll be paid out. "Which is why I have a very big warning: DO NOT sign up to a claims firm now if you're thinking of it, because it is absolutely plausible that you will get the redress without doing anything but the redress firm will want 25 or 30% of the money, even though it hasn't done anything. "So sit on your hands right now, we're waiting to see what happens with the regulator." Martin then broke down how the Supreme Court case itself differs slightly, with three separate cases bundled together. He explained: "One is about the fact that if you didn't know what the commission was and the car broker wasn't acting as a disinterested party, it was effectively bribery. "The second was very similar...now what the court has said is no, they don't have to be independent, they clearly have a relationship with the car finance firm and therefore it rejected the Court of Appeal's decision on those two claims. "Now crucially, that means what was talked about in the widest area, that if you had a car finance arrangement and it hadn't told you what the commission was at all, even if it wasn't excessive, that would mean the car finance was invalid and you're due compensation. That's gone, that's not happening at all." He then revealed that the third case, which HAS been upheld, centres on unfairness under specific circumstances - when commission proves excessive or when brokers falsely claim independence whilst lacking it, deemed unfair with all interest refunded. Martin described these as 'excessive commission arrangements', expressing optimism that a compensation scheme will be unveiled for excessive commissions when the consultation on redress for the previously mentioned discretionary commission arrangements takes place. He told audiences he believes this could mean industry-wide payouts reaching anywhere between £5Bn-15Bn. Martin urged caution to viewers: "My biggest message, don't do anything, don't sign up to a claim firm, sit on your hands, you don't need to do anything." The Financial Conduct Authority (FCA) has pledged to reveal by Monday whether it will launch a consultation on a compensation scheme. The FCA, which stepped into the case, had earlier stated it would outline within six weeks whether it would pursue a consultation on a redress scheme. However, a spokesperson confirmed following the judgment that it would announce whether it will proceed with any such consultation by 8am on Monday "to provide clarity as quickly as possible". Lord Reed revealed the Supreme Court had deliberately chosen to deliver its verdict on a Friday afternoon, beyond trading hours and after markets had shut for the weekend, to prevent any risk of "market disorder".