Car Engine Types: A Comprehensive Guide

Inside the car’s hood lies an amazing machine, when you insert the key or press the start button. The engine is the engine of any vehicle and not all engines are created equal. If you are looking to purchase an auto, or are interested in understanding the vehicle that you already have, or simply curious about the inner workings of a car, understanding the various types of car engines can aid you to make better decisions.

There are a number of types of car engines available today – the traditional petrol engine, the electric motor and a variety of possibilities between. There are advantages and disadvantages of each type and best application. Also, as the demand for cleaner travel grows, new engine technologies are emerging and are quickly altering our expectations from the car.

This guide demystifies all major car engine types, and explains them in terms that are easy to comprehend. Each type of engine will be accompanied by real examples to make it clear what they are different.

Petrol (Gasoline) Engine

The gasoline engine (petrol engine), is the most widely used type of engine in passenger cars globally. It operates by combustion of petrol/air in a pair of cylinders, forcing pistons to move back and forth to generate torque for turning wheels.
People tend to know that petrol engines are smooth, responsive and not so loud. They’re good at high speeds and provide an enjoyable driving experience. But they generate more CO2 emissions than some other options, and may be less fuel efficient when driving in stop-and-go urban traffic.

Diesel Engine

A diesel engine is like a petrol engine, except that it uses a different fuel and ignition system. The diesel engine does not use a spark plug, but it compresses the air so tightly that it becomes very hot, and fuel is injected into this hot air, making it ignite automatically. This is known as compression ignition.

Because of this, diesel engines are very efficient in consuming fuel in comparison to petrol engines, particularly for long journeys on the road. They also produce more torque at lower speeds, making them ideal for heavy vehicles, towing, and long-distance travel. The disadvantages of diesel engines are that they can be louder, emit more Nitrogen Oxides (NOx) and are usually more expensive to maintain.

Electric Motor ( Battery Electric Vehicles – BEV)

Electric vehicles (EVs) have no internal combustion engine. Rather, they are totally electric-powered and run from a large battery pack. This stored electrical energy is then used by an electric motor to give the object motion. The EVs do not emit tailpipe pollution as there is no fuel combustion.

The electric motors also provide much quicker take-off from a standstill, allowing electric vehicles to accelerate quickly. They also have fewer moving parts than combustion engines and, over time, are likely to have lower maintenance costs. The biggest hurdles are still battery efficiency, charging station availability and the initial price tag.

Hybrid Engine

Hybrid cars are a mixture of an electric motor and a small battery with a conventional petrol or diesel engine and a petrol or diesel system. These two power sources complement each other to enhance fuel economy and lower emissions. The electric motor is used to drive the car at low speeds. When travelling fast or under heavy acceleration, the petrol engine will assist.

There are three types of hybrid vehicles, namely mild hybrid, plug-in hybrid (PHEV) and full hybrid. The electric motor is only used to help the combustion engine in mild hybrids and they can’t be powered by the electric motor alone. Full hybrids, such as the Toyota Prius, can be powered by electricity for brief periods. PHEVs use a bigger battery which can be charged from an external source, providing longer electric-only driving time.

CNG (Compressed Natural Gas) Engine

CNG engines operate as petrol engines, but utilise compressed natural gas instead of petrol or diesel. CNG is a much cleaner fuel as it generates far lower levels of CO and particulates. Furthermore, CNG is also less expensive than petrol, making the CNG vehicle economical for those who drive long distances.

An after-market CNG kit can be used to convert many petrol vehicles. There are also some CNG vehicles that are factory fitted. The biggest constraint is relatively the space requirement: CNG tanks consume more space, and require refueling from CNG stations, which are not everywhere.

Rotary (Wankel) Engine

The rotary engine, or Wankel engine, as it is known, is a unique rotary internal combustion engine that features a special rotor — a triangular shape that spins inside an oval-shaped housing instead of pistons. This design leads to a very small, smooth and high rpm producing engine.

The interesting design of the rotary engine has made it too expensive to use in most piston-engined cars, which consume less oil and fuel. It also has difficulty to comply with the modern emission standards. However, Mazda has maintained a continuity with the rotary concept and recently revived it in a novel manner.

Turbocharged Engine

A turbocharged engine is not a standalone engine, but a technology that is used on petrol and diesel engines to boost their performance. More fuel can be burned in the combustion chamber of the engine, and more power is generated from a smaller engine, because of the force of air that a turbocharger can push into the combustion chamber.

Many modern cars now have turbocharged engines as standard as they are a very good balance of performance and efficiency. A small turbocharged engine can generate the same power as a large naturally aspirated engine, and use less fuel. The idea of downsizing is commonly used in the car industry.

Hydrogen Fuel Cell vehicles (FCEVs)

Hydrogen fuel cell vehicles (FCEVs) are one of the most advanced engine technologies in the market. This is a type of vehicle that stores the hydrogen gas in high-pressure tanks, and utilizes it to produce electricity via a chemical reaction in a fuel cell. The electric power then drives the wheels using an electric motor. The only thing that’s given off is water vapour, which means that FCEVs are 100% emission-free at the point of use.

But hydrogen fuel cell technology is still at the beginning stages of mass adoption. However, refuelling facilities are very limited, the production of hydrogen can generate emissions depending on the method used, and the hydrogen vehicles are still costly. Despite the difficulties, several manufacturers are investing a lot of money in this technology for the future.

Finding the Right Engine Type for you

The type of engine you choose will depend on the way and the place you drive. Before making a decision consider the following points:

• Low running costs in stop and go traffic make CNG or hybrid engines the most suitable technology for city commuters who make short trips in the city daily.
• Long-distance or highway drivers benefit the most from the fuel economy of diesel engines.
• Battery electric vehicles should be strongly considered to achieve the lowest running costs and zero tailpipe emissions for buyers who have access to charging infrastructure and want to be more environmentally conscious.
• Turbocharged petrol engines are popular among performance lovers for their power, refinement and practicality.
• For budget-conscious buyers in urban areas in India, a factory fitted CNG vehicle such as the WagonR CNG will be difficult to outbid on TOC.

Frequently Asked Questions (FAQs)

Also, Read –
Basic Car Knowledge: Complete Beginner’s Guide for Every Car Lover