Yep, sounds about right............if you want to cruise 85 mph (like an idiot) then get a V6 or V8 , little 4 cyl motors just don't have ability to keep their higher mpg at such high speeds.

85mph is quite a load on the engine. Yes that is normal

all cars are like that. they each have a certain speed where they are most efficient. go too high or too low and the efficiency drops.

In theory, 2.4L should go faster than 1.8L, but it is not absolute. You should check you engine with ecu tuning tools, which you can get from http://www.obd2life.com/ecu-tuning-tool-...

i drive a 06 kia optima 2.4 4 cyl. car, when i am cruise at 75, the car gets good mileage, however if i cruise my car at 85mph, then the car only gets about 18 miles per gallon.

is this normal? what is he best speed for fuel economy?since this is a 2.4, it should go higher speed than those 1.8L engine cars right?