Currently these are inline-four engines based on the Mazda MZR engine.

1966 – Vauxhall's Slant Four goes into production – the first production overhead camshaft inline-four engine to use a rubber timing belt.

It has a glass fibre body and an 848 cc all-aluminium inline-four engine, providing economical performance.

Ford inline-four engine with cylinder head removed

The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase.

In a specification chart or when an abbreviation is used, an inline-four engine is listed either as I4 or L4 ( for longitudinal, to avoid confusion between the digit 1 and the letter I ).

Today almost all manufacturers of four-cylinder engines for automobiles produce the inline-four layout, with Subaru's Flat-four engine being a notable exception, and so four-cylinder is synonymous with and a more widely used term than inline-four.

The inline-four is the most common engine configuration in modern cars, while the V6 engine is the second most popular.

This inline engine configuration is the most common in cars with a displacement up to 2. 4 L. The usual " practical " limit of the displacement of inline-four engines in a car is around 2. 7 L. However, Porsche used a 3. 0 L four in its 944 S2 and 968 sports cars, the International Harvester Scout was available with a 3. 2 L inline four from 1965 until 1980 and Rolls-Royce produced several inline-four engines of 2, 838 cc with basic cylinder dimensions of diameter and stroke ( Rolls-Royce B40 ).

The Model A Ford was built with a 3. 3 L inline-four engine.

The Isuzu Forward is a medium-duty truck which is available with a 5. 2 L inline-four engine that delivers and.

The Hino Ranger is a medium-duty truck which is available with a 5. 1 L inline-four engine that delivers and.

The earlier Hino Ranger even had a 5. 3 L inline-four engine.

One of the largest inline-four engines is the MAN B & W 4K90 marine engine.

Computer generated image showing the major internal moving parts of an inline-four engine with belt-driven double overhead camshafts and 4 valves per cylinder.

The inline-four engine is much smoother than one -, two -, and three-cylinder engines, and this has resulted in it becoming the engine of choice for most economy cars, although it can be found in some sports cars as well.

The inline-four layout is in perfect primary balance and confers a degree of mechanical simplicity which makes it popular for economy cars.

The Kubota M135X is a tractor with a 6. 1 L inline-four.

However, the inline-four is not a fully balanced configuration.

An even-firing inline-four engine is in primary balance because the pistons are moving in pairs, and one pair of pistons is always moving up at the same time as the other pair is moving down.

Above 2. 0 L, most modern inline-four engines now use balance shafts to eliminate the second-order harmonic vibrations.

Since then, the inline-four has become one of the most common engine configurations in street bikes.

Outside of the cruiser category, the inline-four is simply the most common configuration because of its relatively high performance-to-cost ratio.

In late 1989, the CD range in most of the world was expanded downward with the naturally aspirated 2. 0-litre inline-four.

With more money, more resources and the most powerful engine available in the form of the inline-four turbocharged BMW, it took only until October 1986 for Gerhard Berger to secure the first win for himself, for the team and for a Byrne designed car at the Mexican Grand Prix.

Basic design elements, such as MacPherson strut front and rear suspensions and transverse-mounted inline-four engines, are common to all three generations of MR2, though each generation differs greatly from the next in particulars.

The TR4, in common with its predecessors, was fitted with a wet-sleeve engine, so that for competition use the engine's cubic capacity could be changed by swapping the cylinder liners and pistons, allowing a competitor to race under different capacity rules ( i. e., below or above 2 litres for example ). Standard inline-four engine

In the late 2000s, with auto manufacturers making efforts to reduce emissions ; and increase fuel efficiency due to the high price of oil and the economic recession, the proportion of new vehicles sold in the U. S. with four-cylinder engines ( largely of the inline-four type ) rose from 30 percent to 47 percent between 2005 and 2008, particularly in mid-size vehicles where a decreasing number of buyers have chosen the V6 performance option.

This configuration is a compromise between the smaller inline-four engine and the larger straight-6.

In 1982 Honda introduced the VF series, which used a V4 rather than inline-four motor configuration.

The largest mass-produced inline-four engine in a car has currently the Mitsubishi Pajero 3. 2 DI-D, which has a 3200cc-inline-4 with 165hp at 3500rpm ( in europe 200hp ) and 381Nm at 2000rpm.

The 2009 Yamaha R1 has an inline-four engine that does not fire at even intervals of 180 °.

By comparison an inline-four engine has no free moments of the first or second order, but it does have a large free force of the second order which contributes to the vibration found in unbalanced straight-four designs.

The Citroën C3 is a supermini car equipped with a range of inline-four engines that has been produced by the French automaker Citroën since 2002.

The Bantam 2 / Rustler has a 1. 6 liter inline-four engine.

Image: 2010 BMW Z4 1 -- 01-06-2010. jpg | While the BMW Z4 has plenty of space between front vertical door sill and front wheel, a superficial indicator of the engine being located behind the front axle, only the inline-four variants are FMR

The Green Line has a 2. 4-liter Ecotec DOHC-phaser engine which replaces the standard 2. 2-liter inline-four engine, resulting in the improvement of acceleration time by 1. 0 second.

1. 2 L S-TEC II inline-four engine was updated with features such as dual overhead camshaft ( DOHC ) and timing chain ( older version has timing belt ) system.

It has a, 20-valve ( 5 valves per cylinder ) inline-four engine DOHC producing, or when the other, unused bank of fuel injectors is activated, and over 162 hp ( 120 kW ) in race trim.

In the late 2000s, with auto manufacturers making efforts to increase fuel efficiency and reduce emissions, due to the high price of oil and the economic recession, the proportion of new vehicles with inline-four engines have increased considerably at the expense of V6 and V8 engines.

Originally available with a single-cam 1. 6-liter inline-four or the twin-cam V6, a few more engines were available as development continued.

* Mazda — Variable Inertia Charging System ( VICS ) is used on the Mazda FE-DOHC engine and Mazda B engine family of inline-four engines, and Variable Resonance Induction System ( VRIS ) in the Mazda K engine family of V6 engines.

* Nissan — inline-four engines, V6 engines, V8 engines

* Opel — TWINPORT-modern versions of Ecotec Family 1 and Ecotec Family 0 inline-four engine and inline-three engines ; a similar technology is used in 3. 2 litre 54 ° V6 engine.

* Peugeot — 2. 2 litre inline-four engine, 3. 0 litre V6

* Volkswagen — 1. 6 litre inline-four engine, V6 engines, VR6 engines, W8 engines, V8 engines

The Avenger had a 103 in ( 2. 62 m ) wheelbase and used either a 2. 0 L inline-four engine ( the Chrysler 420A ) or a Mitsubishi-designed 2. 5 L V6.

Engine choices were now limited to Pontiac's Iron Duke inline-four engine and the new corporate 2. 8 L LE2 V6 designed specifically for this platform.

It was available with either a 2. 6-liter inline-four engine rated at or a 3. 1-liter V6 engine made by General Motors ( GM ) which had the same power output as the 2. 6, but had more torque.

Amigos with the GM-sourced, 2. 2-liter X22SE ( Vortec ) inline-four engine are few and far between, mainly because previous owners complained to Isuzu that a V6 needed to be standard.

In 2004, Isuzu dropped the inline-four engine and added the optional 3. 5-liter V6 gasoline direct injection ( GDI ) engine with and of torque.