General Motors assumed Saturn's manufacturing in 2009 when the Saturn brand was discontinued.

A heat engine is a type of system that converts heat or thermal energy into mechanical energy, which can then be used to perform useful work, such as a movement. The below steps record how a heat engine generally work:

1. Heat Input: It all starts when a heat source of high temperature, such as burning fuel, geothermal energy, or solar power, begins to transfer heat energy to the engine.

2. Expansion: The incoming heat causes a working fluid or gas inside the engine to expand. This can cause a piston to move or a turbine to rotate.

3. Work Output: The movement of the piston or rotation of the turbine is turned into useful work. For example, it might power a car's wheels, a generator producing electricity, or any other form of mechanical energy.

4. Heat Exhaust: After delivering work, the fluid or gas will have cooled down, but since it is still hotter than the ambient temperature, it can still be disposed of to a low-temperature heat sink such as the atmosphere or a body of water. This process is often done at a lower pressure to make the exhaust process more efficient.

5. Compression: Lastly, the working fluid or gas is re-compressed to start another cycle. It is then drawn back into the heat source to absorb heat once more, and the cycle begins again.

In all these processes, a heat engine operates under the principles of the laws of thermodynamics, particularly the first (energy cannot be created or destroyed, only changed from one form to another) and the second (in any cyclic process the entropy will either increase or remain the same).

However, it's important to note that no heat engine can be 100% efficient, due to the 2nd law of thermodynamics. Some of the heat always ends up wasted, often lost in the exhaust process.

Yes, nitrogen gas is good for tires for a number of reasons:

1. Nitrogen maintains tire pressure longer than air: Nitrogen molecules are larger and less permeable than oxygen, meaning they stay in your tires longer. Filling tires with nitrogen allows them to retain optimal pressure longer, reducing wear and tear, and improving fuel efficiency.

2. Nitrogen and tires react less to temperature changes: Air expands and contracts with temperature changes, causing the tire pressure to fluctify. Nitrogen isn’t as affected by temperature, leading to more consistent tire pressure.

3. Nitrogen prevents moisture: Filling tires with nitrogen eliminates the moisture content, reducing the chance of internal tire damage.

However, it’s important to keep in mind that the benefits of using nitrogen are more perceivable in certain situations like racing or aviation where precision matters more. For average daily driving, filling tires with compressed air is generally sufficient and more cost-effective.

Make sure you always maintain the right tire pressure, whether you are using air or nitrogen.