Do Cars Really Explode Like in the Movies? Debunking Hollywood Myths

\nYou've seen it countless times in action movies: a car crash followed by a massive, fiery explosion. But how much of this is Hollywood magic, and how much is reality? Let's dive into the science behind car explosions and debunk some common myths.

The Reality of Car Explosions

• Explosions in movies are often exaggerated. In reality, cars don't typically explode into massive fireballs.
• There isn't anything in cars themselves that would enable them to detonate like a bomb.

How Explosions Work

Scientifically, an explosion is a rapid expansion in volume, usually gas, causing a significant spike in air pressure that propagates outward as a shockwave.

Internal Combustion Engines: Controlled Explosions

Cars are propelled by small, controlled explosions within their internal combustion engines. These engines mix gasoline vapor and air, which ignite when exposed to sparks from the spark plugs.

When the fuel (hydrocarbons) burns, it reacts with oxygen, producing carbon dioxide and water. This process releases energy rapidly in the form of heat and light.

Gasoline: Flammable, Not Explosive

Gasoline, or petrol, is highly flammable but not explosive in its liquid form. Gasoline vapors will ignite and explode only when mixed with air at concentrations between 1.3 and 7.1 percent.

• Too Lean: Below 1.3 percent concentration, the vapors are too lean to explode.
• Too Rich: Above 7.1 percent concentration, the vapors are too rich to explode.

In a car's fuel tank, the concentration of gasoline vapors is usually too rich, with very little oxygen present. Without an external heat source, the vapors won't ignite.

The Ford Pinto Myth

In the 1970s, the Ford Pinto gained notoriety for fires caused during rear impacts. However, these fires were due to a design defect related to the fuel tank's positioning.

• Crash tests were performed under worst-case scenarios to illustrate the defect.
• The tests were effectively set up to make the target car catch fire.

Historical records show that the Pinto wasn't significantly more dangerous than other cars produced in the 1970s.

Electric Vehicles: Thermal Runaway

Electric vehicles (EVs) are becoming increasingly popular, but they also face scrutiny regarding their safety. EVs use lithium-ion batteries, which can sometimes experience thermal runaway.

What is Thermal Runaway?

Thermal runaway is an increase in temperature that occurs when the heat created by a defective or poorly installed battery exceeds the amount of heat that can be dissipated.

This can lead to the emission of toxic and flammable gasses, which may collect in a vapor cloud. If a heat source is present, the vapor cloud can ignite and explode.

Are EVs More Likely to Explode?

While EVs can experience explosions, statistically, they are very unlikely to occur. In fact, gasoline cars catch fire roughly 20 times more often than electric cars.

LPG Tankers: A Different Story

Liquefied petroleum gases (LPGs) like propane and butane are used to power vehicles, cook food, and heat homes. LPGs are stored under pressure, making tankers essentially large gas cylinders.

Vapor Cloud Explosions

Most explosions involving LPG fuel are caused by gas leaking into an enclosed space, which is then ignited. These explosions happen externally and aren't caused by a fault in the tank itself.

Boiling Liquid Expanding Vapor Explosion (BLEVE)

Genuine tank explosions are rare but devastating. If a pressurized LPG tanker ruptures, the sudden drop in pressure causes an equivalent drop in boiling point, meaning the contents will instantly vaporize, expand, and explode.

BLEVE explosions are considered some of the most dangerous and powerful non-military explosions that can occur.

Notable Examples

• Chala LPG Tanker Disaster (2012): An LPG truck collided with a concrete road divider and overturned, resulting in a massive BLEVE explosion.
• Boksburg Explosion (2022): An LPG tanker crashed and became jammed underneath a railway bridge, exploding multiple times before a final massive blast.

The Verdict

It is exceedingly rare for gasoline cars, EVs, or LPG tankers to explode. The only time a car will catastrophically explode in dramatic fashion is with the use of explosives or special effects.

Regular passenger cars simply don't have the capacity to cinematically explode. Explosions involving LPG tankers are also very rare, especially in developed nations with robust regulations.

If you see an overturned LPG tanker on fire, don't stick around to watch!