By Lars Mucklejohn UK auto lenders could be hit by up to £16bn in compensation payments after the City watchdog confirmed its probe in historic commission arrangements would look at cases going back to 2007. The probe concerns so-called discretionary commissions, which allowed gave brokers and dealers to raise customers’ interest rates. The Financial Conduct Authority (FCA) confirmed on Wednesday that its review into commission arrangements that led to consumers overpaying would include deals made between April 2007, when the Financial Ombudsman Service first started overseeing the practice, a…