There is 2 stroke gas in 1/5th scale. The problem with 4 stroke is you need a way to introduce oil into the engine using external means. With 2 stroke the oil is mixed in the fuel, which is basically what we run now with nitro. To go 4 stroke you'd need an oil pump and someplace to store the oil until its used, and that means alot of extra weight. I don't think 4 stroke will be that mirco sized anytime soon, but i could see other alternatives to nitro fuels in the future. Stuff like bio deisel might be adaptable and produce good hp and low end torque.