What are the differences between diesel and gasoline?

[HoldenDella]

The main differences between diesel and gasoline lie in volatility, air mixing capability, energy content, combustion method, emission characteristics, price, odor, energy, and color. The specific details are as follows: Volatility: Gasoline is highly volatile, while diesel is not. Air mixing capability: Gasoline mixes easily with air due to its high volatility, which is why gasoline engines use technologies like direct injection and stratified injection to optimize the air-fuel mixture for more complete combustion. Diesel, on the other hand, does not mix as easily with air, leading to incomplete combustion in diesel engines. This results in unburned components being emitted as black carbon particles, which is why diesel vehicles often produce black smoke and have a strong odor. Energy content: Gasoline consists of smaller molecules with hydrocarbon compounds containing about 8-10 carbon atoms, whereas diesel contains 12-15 carbon atoms. When burned, more carbon atoms release greater energy if combustion is complete. Compared to the same volume of gasoline, diesel provides higher energy, making diesel engines more fuel-efficient under similar thermal efficiency conditions. Combustion method: Gasoline engines use spark plugs for ignition, while diesel engines rely on compression ignition. Gasoline molecules are smaller, more active, and have a lower ignition point. Gasoline engines mix air at an ideal ratio and compress it to around 10 times before igniting with a spark plug. Diesel, with its higher carbon content, requires more air and is harder to ignite with a spark plug. Therefore, diesel engines use a compression ratio of 15-18 to compress the diesel-air mixture (compression raises temperature) until it ignites. Emission characteristics: Gasoline burns at high temperatures, and incomplete combustion leads to partial dissociation of compounds, emitting mainly carbon monoxide, hydrocarbons, and nitrogen oxides. Diesel engines have more air but poorer mixing, leading to carbon soot in oxygen-deficient areas. Due to the excess air, diesel engines emit less carbon monoxide and hydrocarbons but produce more particulate matter and nitrogen oxides. Price: Gasoline is more expensive, while diesel is cheaper. Diesel has higher energy content. Diesel does not require a spark plug and self-ignites under high pressure, making it more efficient but heavier and noisier. Gasoline requires ignition, so gasoline engines are smaller and quieter. Odor: Gasoline has a pungent smell, while diesel has a milder odor. Color: Gasoline is lighter in color, while diesel is darker. Additionally, diesel is mainly used in trucks. Diesel engines rely on compression ignition with a high compression ratio (up to 15), resulting in longer cylinder strokes and higher torque, providing better acceleration. Diesel engines operate at lower RPMs, so their power output is generally lower than gasoline engines, resulting in slower speeds. Gasoline is primarily used in passenger cars. Gasoline engines use spark ignition with lower compression ratios, typically 8-11 for naturally aspirated engines and not exceeding 14 for turbocharged ones.

[VanLeah]

I remember when I first drove a diesel car, I noticed it was quite different from a gasoline car. The main difference lies in the ignition method: diesel engines use compression ignition, where the fuel ignites on its own due to compression, so the engine sounds rougher and more rumbly. Gasoline engines, on the other hand, use spark ignition with spark plugs, making them quieter and smoother. In terms of fuel efficiency, diesel has a higher energy density—with the same tank of fuel, you can drive an extra 100-200 kilometers on the highway. My old diesel car had significantly lower fuel consumption than gasoline cars. When it comes to driving feel, diesel cars offer higher torque, providing strong acceleration from a standstill, making them ideal for hauling heavy loads or long-distance driving. Gasoline cars rev up faster, offering more agility for lane changes in the city. Maintenance-wise, diesel engines are more durable but have more expensive parts, and preheating in winter can be a hassle. Emissions also differ: diesel emits more particulate matter, while gasoline produces less CO2. Nowadays, diesel is more popular for long-distance driving, while gasoline is more practical for city commuting. I’ve also tried hybrid cars, which combine the best of both, though pure electric vehicles are on the rise. Overall, diesel and gasoline each have their pros and cons—the choice depends on your driving habits and needs.

[StSimon]

From a technical perspective, diesel and gasoline are fundamentally different. Firstly, the ignition principle: diesel relies on high-pressure compression ignition, where the engine compresses air to high temperatures, and the fuel self-ignites upon injection; gasoline uses spark plugs to ignite the air-fuel mixture. This makes diesel more efficient and energy-dense, allowing vehicles to travel farther per liter of fuel, especially noticeable in long-distance driving for fuel savings. In terms of power output, diesel engines deliver higher torque, making them suitable for trucks or SUVs that require towing; gasoline engines achieve higher RPMs and faster acceleration. Regarding emissions, diesel engines emit more particulate matter and nitrogen oxides, requiring additional filters; gasoline engines emit lower CO2 levels. Cost and maintenance: diesel fuel is slightly cheaper, but diesel vehicles have a higher initial cost, and turbocharged diesel engines may incur higher maintenance expenses; gasoline vehicles are quieter and more comfortable. These differences stem from fuel characteristics and engine design, though modern vehicles have seen significant optimization, such as cleaner diesel reducing pollution. Additionally, be cautious when refueling to avoid misfueling, as using the wrong fuel can cause vehicle issues. Overall, understanding these distinctions is crucial for vehicle selection.

[MacAlaina]

From an economic perspective, diesel is significantly more cost-effective than gasoline. In terms of fuel expenses, diesel has a lower price per liter and delivers more kilometers per liter. For instance, driving a diesel car on long-distance trips can save me 20% on fuel costs. Although diesel vehicles have a higher upfront cost, they prove worthwhile in the long run, especially for daily commuters. Regarding maintenance, diesel engines have a longer lifespan but require more expensive part replacements and frequent oil changes. Gasoline cars, on the other hand, offer simpler routine maintenance and are more economical for city driving. Emissions-wise, diesel produces more smoke, though modern vehicles are equipped with DPF (Diesel Particulate Filter) systems; gasoline exhaust is cleaner. Personally, I opt for diesel for highway driving to save on fuel costs and allocate the savings to household expenses. With the rise of electric vehicles, the advantages of diesel are diminishing. Ultimately, the choice depends on individual budgets and usage needs.