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I think it's one of the most popular things in action films: Cars exploding.

In reality, a car explodes very rarely, even when it gets shot. However, what fuel type tends to explode more?

Diesel

Diesel is similar to kerosene. It has a relatively high ignition temperature. So, it's very unlikely that diesel will be ignited by bullets.

Kerosene is vaporizing at a specific temperature. Below this temperature, kerosene is perfectly secure, but when exceeding it, the vapor is a highly-explosive mixture. And this mixture can be ignited easily.

I don't know if it's the same with diesel, but as it is similar to kerosene, it could be.

Petrol

Petrol can be ignited easily. Maybe even by a bullet. There is also a petrol-vapor, that is explosive as well.

So, what type of fuel would make most sense if we see a car exploding in an action film?

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  • When you are saying Cerosene, do you actually mean Kerosene? I looked online wondering if this may be a different way to spell kerosene in Austria, but I didn't find anything. Cerosene is actually a completely different chemical makeup ... there is such a thing, it just isn't Kerosene. Cerosene has the element cerium in it, which is where it gets it's name. These two are completely different animals.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 15, 2017 at 20:47
  • @Pᴀᴜʟsᴛᴇʀ2 Thank you. I thought it's Cerosene in English. Of course I mean the fuel type Kerosene, used in planes. I am from Austria by the way, not from Australia :)
    – Noah Krasser
    Jun 15, 2017 at 20:50
  • I'm terribly sorry. Please forgive me for misreading that ... happens to the best of us, I guess!! :o)
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 15, 2017 at 20:53
  • @Pᴀᴜʟsᴛᴇʀ2 No problem, very normal for us Austrians :)
    – Noah Krasser
    Jun 16, 2017 at 9:12
  • TV is not Reality, really.....
    – Moab
    Jun 18, 2017 at 2:30

2 Answers 2

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There are many factors. There is the volatility, where gasoline wins. There is the specific energy per unit volume, where diesel wins. In the end, it is the mixing of the fuel and air which drives the ultimate bang.

We can all image that a spray can of gasoline can make quite a volatile environment, and is easily ignited. But consider a fuel-air bomb, with effectively ignited diesel efficiently atomized, and then ignited. A bang rivaling small nukes and very devastating.

My vote for biggest bang is for diesel, as it has effectively been demonstrated as providing just that, in fuel-air bombs. The energy content per unit volume is higher than gasoline, so the potential is greater. It is not as volatile, but can effectively be ignited.

But if you are trying to start a fire, and you can get the ideal mixture of about 14:1, and you only have one weak spark, I would always try gasoline to start the fire.

Addendum #1

The lower flammable limit or lower explosive limit (LFL or LEL) of gasoline is 1.4 percent; the upper flammable limit or upper explosive limit (UFL or UEL) is 7.6 percent.

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  • I looked in quite a few places and cannot find anything which shows diesel fuel or kerosene being used in the MOAB or any other thermobaric bomb. Do you have any references showing this? Also, kerosene has less energy density than does gasoline by quite a significant amount (42.8 MJ/Kg v. 46.4 MJ/Kg - respectively). Diesel does have a higher energy density than gasoline, but just by a bit ... plus the question is asking specifically about kerosene (or jet fuel), not about diesel. Please see Energy Desnity on Wiki.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Jun 15, 2017 at 21:56
  • Previously, such explosions were most often encountered in flour mills and their storage containers, and later in coal mines; but, now, most commonly in partially or fully empty oil tankers and refinery tanks and vessels, including an incident at Buncefield in the UK in 2005 where the blast wave woke people 150 kilometres (93 mi) from its centre.[4] Health and Safety Environmental Agency, 5th. and final report, 2008.
    – mongo
    Jun 15, 2017 at 22:30
  • The question body specifically addressed diesel, which compared volumetrically to gasoline is 139,000 BTU/gal vs 124000 BTU/gal or about 12% more energy/gal, which I consider significant. (Engineeringtoolbox.com) Figures nominal, and avoids winter vs summer gasoline, etc.
    – mongo
    Jun 15, 2017 at 22:38
  • The use of diesel in improvised fuel air bombs was discussed with BDA and counter terrorism analysts. I use it as an example that atomized diesel fuel (or flour or ethylene oxide) can effectively be burned in a fuel-air blast. But the OP did not ask about flour, he had two block titles of Diesel and Petrol.
    – mongo
    Jun 15, 2017 at 22:41
  • Diesel has 10 times the thermal energy than gasoline.
    – Moab
    Jun 19, 2017 at 0:28
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If you want some really explosive vehicle fuel then perhaps Nitromethane mixed with the oxidizer Nitrous Oxide would have a better chance of exploding. Especially since Nitromethane can actually detonate like a high explosive under certain conditions.

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