Listen to this article Both manufacturers were forced to retire cars involved in the battle for victory at last weekend’s Rally Sweden after suffering failures with the control hybrid unit. Under the current FIA regulations surrounding the new hybrid component, drivers and teams are unable to continue if warning lights appear, or if there is an absence of active lights on a hybrid unit, even if the car can still operate using its internal combustion engine. In this situation Rally1 cars are effectively put into quarantine with teams unable to touch them as a safety precaution until given an all-clear by hybrid unit suppliers Compact Dynamics and the FIA. Hyundai’s Ott Tanak and Toyota’s Elfyn Evans were the first drivers to fall foul of the rules. A red light appeared on Tanak’s hybrid unit while sitting …