From Longman Dictionary of Contemporary Englishunleadedun‧lead‧ed /ʌnˈledɪd/ adjective TTCunleaded petrol does not contain any lead —unleaded noun [uncountable] Ben’s car only takes unleaded.
Examples from the Corpus
unleaded• Like any big-block V-8 fueled by gasoline, this engine chugged regular unleaded.• Can you confirm that Land Rover V8 will accept unleaded fuel? 4.• Most outdid Torreson's $ 1.70.9 per gallon of unleaded gasoline by a cent at $ 1.69.9.• Arco spokesman Scott Loll said 55 customers' cars broke down after pumping the regular, unleaded gasoline.• Jet, which already sells cut-price petrol, will knock 12p off a gallon of unleaded, reducing it to £199.6p.• However, in more rural counties, unleaded regular can still be found for $ 1. 19 a gallon.• But you couldn't feel smug about filling up your tank with unleaded while all that was going on.• If I use unleaded will my engine be less powerful? 