# Straight-five engine

A straight-five engine, also called an inline-five or I5, is an internal combustion engine with five cylinders arranged in a single row along one crankshaft. It sits between the four-cylinder and six-cylinder layouts: longer and smoother than a four, shorter and narrower than a six. The configuration first reached series production in 1938 in the Lancia 3Ro truck, while the 1974 [Mercedes-Benz](https://www.edgepedia.org/mercedes-benz) diesel was the first series-production passenger car with a five-cylinder engine, and the layout became closely identified with Audi, which has built five-cylinder engines almost continuously since 1976 and today offers the last five-cylinder engine in series production, the 2.5 TFSI in the RS 3<sup>[15](https://www.regioesercito.it/pages/lancia3ro.html)</sup>.

| Key fact | Detail |
|---|---|
| First passenger-car use | Mercedes-Benz OM617 3.0-liter diesel, 79 hp, in the 240 D 3.0, 1974; the first five-cylinder engine in a series-production passenger car<sup>[1](https://media.mbusa.com/news/a-bridge-between-tradition-and-digitalization-the-new-e-class)</sup> |
| Firing order | 1-2-4-5-3, with a firing interval of 144 degrees of crankshaft rotation<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup> |
| Crankshaft | Five throws spaced 72 degrees apart, one per cylinder<sup>[3](https://fliphtml5.com/kbpub/nsdi/DMD_2013-_Automotive_technology_principles_diagnosis_and_service_4th_edition/381/)</sup> |
| Signature maker | Audi, from the 1976 EA 828 in the second-generation Audi 100 through the current 2.5 TFSI<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup> |
| Current output | Audi RS 3 2.5 TFSI: 294 kW and 500 Nm, 0-100 km/h in 3.8 seconds<sup>[4](https://media.audi.com/is/content/audi/country/za/assets/brochure/2025/Audi-RS3-Brochure-2025.pdf)</sup> |
| Status | The RS 3's five-cylinder is the final one in series production; Audi has confirmed its production ends after the current model<sup>[5](https://arstechnica.com/cars/2025/07/the-2025-audi-rs-3-is-a-five-cylinder-firecracker/)</sup> |

## Why five cylinders

The straight-five exists mainly as a packaging compromise. For a transverse-engine, front-wheel-drive car, it is only slightly longer than an inline-four but much narrower than a V6, so it offers six-cylinder-class displacement in an engine bay sized for a four. Audi faced the mirror-image problem: its longitudinal-engine, front-drive layout put the engine ahead of the front axle, and an inline-six would have been too long and too nose-heavy. A V6 was considered and rejected because it would not run as smoothly as an inline-five and shared few components with the company's four-cylinders<sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup>.

Mercedes-Benz, building longitudinal rear-drive cars where an inline-six packaged easily, never saw the need for a gasoline five; its five-cylinder was a diesel, developed directly from the four-cylinder OM616 by adding a cylinder<sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup><sup> • </sup><sup>[7](https://porschecarshistory.com/wp-content/old/lib/magazines/MD/Mercedes%20Driver%20Magazine%20-%20February%202018.pdf)</sup>.

## Firing order and sound

An inline-five fires once every 144 degrees of crankshaft rotation, since 720 degrees of the four-stroke cycle divided by five cylinders gives 144. The crankshaft carries five throws at 72-degree intervals<sup>[3](https://fliphtml5.com/kbpub/nsdi/DMD_2013-_Automotive_technology_principles_diagnosis_and_service_4th_edition/381/)</sup>. The usual firing order is 1-2-4-5-3, chosen so that cylinders directly adjacent and cylinders far apart alternate, which Audi describes as the setting for the smoothest possible operation<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup>.

The odd cylinder count produces the configuration's distinctive uneven exhaust warble, a sound that has become part of the engine's appeal. Measured refinement falls between its neighbors: idle residual vertical acceleration of a 2021 Audi RS 3 measured 0.28 m/s² (RMS), against 0.14 m/s² for a [BMW B58](https://www.edgepedia.org/bmw-b58) inline-six and 0.42 m/s² for a Ford EcoBoost 2.3L inline-four<sup>[8](https://motorgearmatrix.com/smart-driving/advantages-and-disadvantages-inline-five-cylinder-engine)</sup>. Honda, which built a longitudinal five for the Acura Vigor from 1989, added a five-point engine mount system and a torsional damper pulley to control cabin noise and crankshaft rumble<sup>[9](https://www.jstage.jst.go.jp/article/hondatechnicalreview/2/0/2_1990_2_2/_article/-char/en)</sup>.

## Mercedes-Benz and the first production five

Mercedes-Benz put the first five-cylinder engine in a series-production passenger car in 1974: the OM617, a 3.0-liter diesel with 79 hp, installed in the W115 240 D 3.0, a model normally powered by a 2.4-liter four<sup>[1](https://media.mbusa.com/news/a-bridge-between-tradition-and-digitalization-the-new-e-class)</sup><sup> • </sup><sup>[10](https://www.classicandsportscar.com/en-au/gallery/50-years-audis-five-cylinder-engines)</sup>. The engine was later offered with exhaust-gas turbocharging in the 300 SD S-Class, and it remained in production into the 1990s<sup>[7](https://porschecarshistory.com/wp-content/old/lib/magazines/MD/Mercedes%20Driver%20Magazine%20-%20February%202018.pdf)</sup>.

## Audi and the gasoline five

Audi's five-cylinder story began in August 1976 with the second-generation [Audi 100](https://www.edgepedia.org/audi-100). Engineers debated inline-five and inline-six options; the six was ruled out for space and weight-distribution reasons, and the company chose the five, a layout known but little used in high-volume production. Derived from the EA 827 four-cylinder that had appeared in the [Audi 80](https://www.edgepedia.org/audi-80) in 1972, the new engine was designated EA 828. It carried over the belt-driven overhead camshaft, 88-millimeter cylinder spacing, cylinder diameter, and valve, spark plug, and injector layout, while the longer crankshaft required a larger main bearing diameter and the stroke grew to 86.4 millimeters<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup>.

The first version displaced 2,144 cc and produced 100 kW (136 PS), taking the Audi 100 5E to 100 km/h in 9.5 seconds with a 190 km/h top speed<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup>. Audi added a 2.0-liter naturally aspirated five-cylinder diesel in 1978 (51 kW), and in 1979 the first turbocharged five-cylinder gasoline engine in the Audi 200 5T (125 kW); with displacement fixed, turbocharging was the only route to substantially more power<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup>.

**The quattro era.** In March 1980 Audi unveiled the quattro at the Geneva Motor Show with a turbocharged five producing 147 kW (200 PS). Combined with intercooling and quattro permanent all-wheel drive, the engine carried Audi to rally success including two manufacturers' and two drivers' world championships, and [Group B](https://www.edgepedia.org/group-b) rally versions reached roughly 500 hp<sup>[2](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)</sup><sup> • </sup><sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup>.

Audi dropped the five-cylinder from its own lineup in 1997, then revived it with a bespoke transverse turbocharged unit for the 2009 TT RS, rated at 340 hp and later 400 hp in the TT RS and RS 3<sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup>. An international jury of automotive journalists voted Audi's 2.5 TFSI Engine of the Year in its class nine consecutive times from 2010<sup>[11](https://www.audi-mediacenter.com/en/press-releases/powerhouses-five-cylinder-engines-at-audi-14239/download)</sup>.

## Other manufacturers

Volvo made the five-cylinder a centerpiece of its lineup. Its transverse inline-five debuted in the 1991 Volvo 850 GLT, a DOHC 20-valve unit with variable induction designed as a member of Volvo's modular engine family alongside its six-cylinder sibling, sharing components and machining lines for cost-effective production<sup>[12](https://saemobilus.sae.org/papers/volvo-5-cylinder-engine-4-valve-technology-a-new-member-volvos-modular-engine-family-911906)</sup>. Volvo offered fives in most of its models until moving to an all four-cylinder lineup in 2016<sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup>.

Honda introduced its G-series 2.0- and 2.5-liter fives in Japan-market sedans in 1989, mounted longitudinally with three cylinders behind the front axle for weight distribution; the engine reached the United States in the 1992 Acura Vigor (176 hp) and continued in the 2.5 TL until 1998<sup>[13](https://www.caranddriver.com/features/g15087001/five-alive-all-the-notable-cars-we-know-with-five-cylinder-engines/)</sup>. Fiat's 2.4-liter JTD diesel five appeared in the [Alfa Romeo 156](https://www.edgepedia.org/alfa-romeo-156) and Fiat Marea from 1997, later growing to 207 hp in the Alfa 159<sup>[13](https://www.caranddriver.com/features/g15087001/five-alive-all-the-notable-cars-we-know-with-five-cylinder-engines/)</sup>. Ford borrowed the Volvo five for the second-generation Focus ST and RS, with the Focus RS500 making 345 hp from 2.5 liters, and also built a five-cylinder diesel for the Transit van. VW built a VR-5 based on its narrow-angle VR-6, and GM offered a five-cylinder in the first-generation Colorado and Canyon pickups and the [Hummer H3](https://www.edgepedia.org/hummer-h3)<sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup>.

## Decline and current status

The technology that created the most notable five-cylinders, turbocharging, also removed the reason for the layout. Modern turbocharged four-cylinders deliver comparable power with better fuel economy and emissions, without the cost and complexity of a fifth piston, and stricter safety packaging requirements make the inline-five's extra length harder to accommodate<sup>[6](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)</sup>.

The Audi RS 3 is the last five-cylinder holdout in production cars<sup>[5](https://arstechnica.com/cars/2025/07/the-2025-audi-rs-3-is-a-five-cylinder-firecracker/)</sup>. Its 2.5 TFSI produces 294 kW and 500 Nm and launches the car from 0 to 100 km/h in 3.8 seconds<sup>[4](https://media.audi.com/is/content/audi/country/za/assets/brochure/2025/Audi-RS3-Brochure-2025.pdf)</sup>. Audi has confirmed that the RS 3's 2.5-liter five-cylinder engine ends production after the current model's run<sup>[14](https://www.youtube.com/watch?v=pLgj6dse28I)</sup>.

## References

1. [A Bridge Between Tradition and Digitalization: The New E-Class, Mercedes-Benz Media](https://media.mbusa.com/news/a-bridge-between-tradition-and-digitalization-the-new-e-class)
2. ["1-2-4-5-3: 50 years of Audi five-cylinder engines", Audi MediaCenter](https://www.audi.com/en/press-releases/1-2-4-5-3-50-years-of-audi-five-cylinder-engines-new-special-exhibition-at-the-audi-museum-mobile-18195)
3. [Automotive Technology: Principles, Diagnosis, and Service, 4th edition (crankshaft and firing interval)](https://fliphtml5.com/kbpub/nsdi/DMD_2013-_Automotive_technology_principles_diagnosis_and_service_4th_edition/381/)
4. [Audi RS 3 Brochure 2025](https://media.audi.com/is/content/audi/country/za/assets/brochure/2025/Audi-RS3-Brochure-2025.pdf)
5. [The 2025 Audi RS 3 is a five-cylinder firecracker, Ars Technica](https://arstechnica.com/cars/2025/07/the-2025-audi-rs-3-is-a-five-cylinder-firecracker/)
6. [The Rise and Fall of the Five-Cylinder Engine, Road & Track](https://www.roadandtrack.com/car-culture/a44910672/five-cylinder-engine-history/)
7. [Mercedes Driver Magazine, February 2018 (OM617 development)](https://porschecarshistory.com/wp-content/old/lib/magazines/MD/Mercedes%20Driver%20Magazine%20-%20February%202018.pdf)
8. [Advantages and Disadvantages of the Inline-Five Cylinder Engine, MotorGearMatrix](https://motorgearmatrix.com/smart-driving/advantages-and-disadvantages-inline-five-cylinder-engine)
9. [Honda New In-line Five Cylinder Engine: Noise and Vibration Reduction, Honda R&D Technical Review](https://www.jstage.jst.go.jp/article/hondatechnicalreview/2/0/2_1990_2_2/_article/-char/en)
10. [50 years of Audi's five-cylinder engines, Classic & Sports Car](https://www.classicandsportscar.com/en-au/gallery/50-years-audis-five-cylinder-engines)
11. [Powerhouses: Five-Cylinder Engines at Audi, Audi MediaCenter](https://www.audi-mediacenter.com/en/press-releases/powerhouses-five-cylinder-engines-at-audi-14239/download)
12. [The Volvo 5-Cylinder Engine with 4-Valve Technology, SAE Paper 911906](https://saemobilus.sae.org/papers/volvo-5-cylinder-engine-4-valve-technology-a-new-member-volvos-modular-engine-family-911906)
13. [Five Alive: All the Notable Cars We Know with Five-Cylinder Engines, Car and Driver](https://www.caranddriver.com/features/g15087001/five-alive-all-the-notable-cars-we-know-with-five-cylinder-engines/)
14. [Audi Confirms RS3 5-Cylinder Ends Production This Year, Matt Maran Motoring (YouTube)](https://www.youtube.com/watch?v=pLgj6dse28I)
15. [Regio Esercito](https://www.regioesercito.it/pages/lancia3ro.html)

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*Topic: Encyclopedia › Technology and the built world › Transport and spaceflight › Road transport › Automobiles › Automobile engines*

*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*

*Copyright 2026 EdgeChat AI, a subsidiary of Biostate AI.*

License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license