Internal combustion is a practical (if undesirable) power source on Earth because there are easy-to-carry, easy-to-store fuels such as gasoline and diesel that can easily be pumped and metered into an engine and reacted with abundant atmospheric oxygen to heat an abundant working fluid (mostly atmospheric nitrogen) to produce mechanical power.
OK, carry your own oxygen and burn with the methane on Titan, sure, but oxygen is hard to store in quantity - you'd be unlikely to attain the sort of energy density with a hypothetical Titan vehicle that we can get here on Earth with gasoline or diesel fueled vehicles.
As stated in other answers, it is, in any event, unlikely you would find naturally occurring chemical reactants in abundance, ready to harvest in any sort of powerplant, on any world unless there was some sort of biological process at work dumping excess energy from some other source (like radiation from a host star) into chemical separation.
Everywhere we have been able to look so far (admittedly only within our own solar system), we find chemical soups on various worlds, but no neatly separated stores of reactants like we have on Earth. Even here we see phenomena like forest fires, triggered by lightning, increasing global entropy combining wood and oxygen to make water vapour, carbon dioxide, and ash. It's just that there's so darn much photosynthetic life that what gets spontaneously consumed by fire is promptly replaced.
The key point is: no celestial body examined to-date has an "exploitable" atmosphere like we have on Earth. As soon as we find one, chances are, we will have found extraterrestrial life.
FWIW: Internal combustion engines are relatively inefficient devices for converting stored energy into mechanical power - at best, only about half the available chemical energy is converted into useful work; the rest ends up as waste heat. They are only practical because of the energy density of the fuel source, power density of ICEs, and the economics of both the devices and the fuels. If you start making chemical substitutions, the economics and practicality can go away, and other options can become more favorable, like fuel cell electric or battery electric.