Don't know about helium, but water was used in the very early days. It is called the steam engine. You could also run a car on coak, as they did in WW2. The only problem was you had to stoke a fire or heat sorce, well before driving it.

Helium could only be used if stored compressed and released through a turbine or something... and then air or nitrogen would probably work better. It contains no useful chemical energy. The only way of using water as fuel that I have heard intelligently discussed would involve some kind of not-yet-discovered or invented cold fusion that could produce enough energy to dissociate the water and fuse the hydrogen and enough extra energy to run the vehicle. This is not in the foreseeable future. Bottom line: it may be possible, but not with current technology. Even if it becomes technically possible, it is unlikely to ever become practical to build a vehicle which uses only water as fuel.

No helium cant fuel cars yet but in the future helium can be used to fuel cars but you might not be alive by then.

Both are a distinct impossibility in conbustion engines. However with some of the power cell technology I have seen, water figures prominently in them but only as a by-product or reaction agent.

Yes, you can use them together to create electricity (I will tell you how in a minute) and then run the car like the elevated trains that run on electricity from either overhead cables, or 'the third rail'. First you get two pullys, one of them at the bottom of the ocean, or very deep-the deeper the better, and the other at the top. Put a cable of Xylon or whatever around the pullys (top pully can be on a floating platform, bottom pully anchored into huge cement block. Take a large enough metal container to sink with the compressed liquid helium on board-which creates power by turning a turbine with the turning top pully. Then at the bottom the compressed liquid helium would be released into a balloon of sorts, or inverted metal container which would empty of air, just like an upside down cup would that you blew bubbles into. This would rise with ever increasing force as the gas expanded. You can put as many as these liquid-gas/can/ballon(gas)can devices as you want on the cable system which would increas force on the looping cable. Of course you would use some of this power to compress the gas again-but the deper your cable the more it would pay off, but I have an idea on how compress it that is separate from this with almost no power. Anyway you need to have a mechanical gas release valve that is automatic at the bottom depth, or activates when inverted(as soon as it is on the rising side so it displaces the water-thus the rising force). (I hope this helps you with your car, but still it will run on electricity-powerd by water and helium without using them up.) Or you can have the helium raise a sail that you use to power the car, and drink the water to let you live while driving. I think it would be awkward going under bridges or powerlines, and barring that I still think you may get pulled over a lot with this last one.) or just use the helium to rais your craft at an agle upwards-thus going forward (u need no wind for this to work, unless it is at your back), then turn on the de-humidifier in the craft until it takes enough water out of the atmosphere until the crafts noses down-sinking thus going forward the last half of your trip, or for long trips repeat above. This would work if you add a solar powered de-humidifier, or just crank it by hand/feet. What say geniuses? Do I get an honorary degree? Vote accordingly now.

My second method would be to have a tube that goes as deep as you like(or materials permit) and would not need to be very deep at all, lets say 50 feet. The tube is open at the top to allow the atmosphere to come in (air). At the bottom is a can shapped valve that takes air in and then rotates the compartment around to the outside, where it can fill an upside down bucket hooked to a cable that pulls the cable (that is looped on pullys one at the bottom of the water, and one at the surface). This would work much better than my liquid helium idea because no compression is needed. After the air is released at the bottom water would be displaces by a metal bar that rotates counter to the valve-evacuating the valve chamber inside the air tube that goes to the surface. So all you do is rotate the valve to get air from the tube that goes to the surface, then displace the water with the metal bar. c o Valve---> cxO x o c 0 Crude drawing but the C's are the open valves that rotate into the pipe(which is invisible in this drawing, but it goes only around the two x axis' and around the large O only.)and the c's rotate out into the water to release the gas. The o's are the metal bars that fill up the valve to displace the water so it does not get into the tube or pipe. This is how to make a perpetual motion machine that produces HUGE power surpluses. I can draw a better valve if you like, but I think you will get the principal from my description. You can do this in your back yard by diging a deep tubular pit with a tube inside another tube, the outer tube filled with water. Or you can dig a pit and use a stirling engine to take advantage of the temperature difference between the air above the surface, and the ground below the surface. The more extreme the weather hot or cold, the better the machine would work. (or dig deep enough to get down to where the ground gets really hot for your differential)-keep going deeper and you can eventually boil water and run a turbine! I see my valve pic changed once I hit submit as the lines got re-formatted.

You can use a stirling engine using water and helium. Use that paper that heats up when you rub it to make or line the hot cylinder where the helium would expand greatly driving your piston one direction (or drive your flywheel). Then the other end of the piston would be cooled by the water, working better in winter even, or just evaporatively cool in summer especially with the wind created by your driving. Just add water, and conserve your helium in the enclosed cylinder.

Water can be fractured into hydrogen and oxygen by electricity, and then used in a hydrogen fuel cell, which is under development. It would be a smaller version of what the Space Shuttle uses to produce electrical power and drinking water. Thus, the car itself would be electrical, but would be fueled by hydrogen, and the only exhaust would be water vapor (and very pure water, at that). Such cars are expected within the next 15 to 20 years. As for helium... Probably not. It's not easy to get energy out of. Compressed air would be just as good in any possible application.