what do you mean by this: fuel economy highway(1/100km):7.8

1997 Chevrolet Camaro Performance & Efficiency Standard Features  
-3,790 cc 3.8 liters 6 V 90? front longitudinal engine with 96.5 mm bore, 86.4 mm stroke, 9.4 compression ratio, cast iron block, cast iron head, overhead valve and two valves per cylinder
-Unleaded fuel
-Fuel economy EPA highway (l/100km): 7.8
-Multi-point injection fuel system
-Main 59 liter fuel tank
-Power: 149 kW , 200 HP @ 5,200 rpm; 225 ft lb @ 4,000 rpm