I heard a gallon of gas is only about 20% efficient in a car, if this is true what is built wrong with the car

Question

I heard a gallon of gas is only about 20% efficient in a car, if this is true what is built wrong with the car

Answer 1

appx 50% of the fuel doesn't get burned in the engine.  Thats why we have catalytic converters.  The catalytic converter is designed to burn the waste fuel.

A large portion of the fuel that does get burned in the engine produces heat, not pressure to make the piston move.  That heat is why engines have cooling systems.  If we could capture and use the waste heat (both from the engine and the catalytic converter) we could almost double a car's fuel economy.

The problem has been known for about 100 years...  The solutions proposed so far have proven too heavy, inefficient and expensive to bother building.

Answer 2

The environmentalist have already tweaked our cars to reduce the pollution. They don't under stand what they have done. What they were after is to reduce the NO2 as photo chemical smog. The problem by reducing the burning temperature they reduced the efficiency of the engine . They also increased the CO that the motor produced  which is the real pollution because it will kill you.

Answer 3

Biggest answer is heat and friction.  Heat produced by burning gasoline does not make your car move.  A radiator is bad for efficiency.

Friction in the engine, friction in the transmission, friction in the drive line, friction in the tires all reduce the efficiency.

Emission controls are also a culprit.  For a catalytic converter to work the air/fuel ration has to be around 14.7 to 1,  to save gas you want the ratio around 20 to 1.  But then the Nitrogen Oxide (smog) and Carbon monoxide levels from the converter would be to high.

Actually the amount of blow by (unburnt fuel) is much less than 50%.  If it were around 50%  the catalytic converter would be glowing red or melting and the tailpipe would be flowing a fairly decent amount of water out of it.

Answer 4

Today, automakers offer close to 200 models that have EPA-estimated highway ratings of 30 miles per gallon or more.And, new models are increasingly available with highly fuel-efficient technologies like variable valve timing, continuously variable transmissions and more. Ongoing advancements by our engineers are leading to even greater fuel economy gains that will significantly reduce fuel consumption. Their work is helping us continue to strive to make new cars and light trucks more fuel-efficient than ever before.

(Check out the link below for lots of info).