While modern day Jeeps use a variety of engines, the most common one, and the one found in my own Jeep is a 2.0L with a plug in hybrid system, which provides 25 miles of electricity per charge. The Jeep I have has 270 horsepower, but some Jeeps have as low as 200, and others as high as a staggering 500. When the Jeep first was created the engine it used was the Willys "Go Devil" 4 cylinder. Some common issues in modern day Jeeps are; rust, transmission issues, coolant leaks, and suspension wear(death wobble).