Everyday to Exotic/YouTubeRegardless of whether we're looking at the biggest-capacity V8 engines or the smallest-displacement V12s, or anything in between, engines are a core part of what drives a gearhead to be a gearhead. And one engine configuration that deserves its moment under the spotlight is the humble six-cylinder, be that inline or V. These are engines we see less and less of these days, thanks to the popularity of downsizing, but many decades ago six-pot engines were beloved for their smoothness and performance upgrades over four-cylinder lumps.While some of the more famous six-cylinder engines sport large displacements, like Jeep's AMC-supplied 4.0-liter inline-6, or Nissan's award-winning VQ-family 3.5-liter V6, a number of far-smaller sixes deserve some glory just as much. Engines like these tend to hail from the earlier decades of motoring, and we've highlighted five here from an assortment of automakers. Most are dinky inline units, with capacities between 1.1 and 1.5 liters, although we've also included a famously diminutive V6. So forget heady outputs, clever hybridized units, and monstrous turbos. Get in gear for refinement, clever packaging, and laughably small footprints.Read more: What Are The Rarest Cars Featured On Jay Leno's Garage?5. Lancia Aurelia 1.75-liter V6Thepalmer/Getty ImagesOur first entry hails from Italy, and it's our V6, a 1.75-liter engine that moved the earliest Lancia Aurelias, before Lancia increased displacement in the ever-relevant quest for more power than its 56 hp. This was, in fact, the first V6 to have made its way into a production car in series production. It used a single camshaft that sat in the center of the all-alloy engine. It had a pushrod construction and boasted hemispherical combustion chambers, a design often incorrectly attributed to Dodge. Fuel was typically fed via a single carburetor, although some hot 2.0-liter iterations boasted a pair.AdvertisementAdvertisementThough a 1.75-liter V6 is certainly no monster, there was an even smaller variant of this engine. It was Lancia's original prototype for the V6, and it sported a displacement of just 1.5 liters, or 1,569-cc to be precise. These prototype engines were tested between 1946 and 1948, while the production model with its larger 1.75-liter mill arrived in 1950.4. Vauxhall 1.5-liter inline-6Heritage Images/Getty ImagesNow we pack our bags and leave for England. This next engine is something of a "big block" in comparison with the next three mills, but with a capacity of just 1.5 liters, it's still minuscule in comparison to what we typically see in a six-pot.This six belongs to Vauxhall, and can be found under the hood of its mid-1930s Light Six. A handsome sedan, the Light Six was available with two engines; a 14-horsepower 1.8-liter unit, or the more modest 12-horsepower 1,530-cc engine. It was a stylish, well-equipped car for the time, boasting independent front suspension and a four-speed synchromesh transmission. Likely of more interest to buyers was the 195-pound ($826) starting price. A six-cylinder sedan for under 200 pounds was clear value for British buyers, and with 26,000 finding a home within the first year on sale, it's clear to see the Light Six was an immediate success.Unlike some of the cars featured in this article, the Light Six is not an antique unicorn, but an accessible classic with a small number changing hands from time to time. Buyers in the U.S. might be hard-pressed to find them close to home, but in Vauxhall's homeland, smart ones have recently been seen to change hands for less than $10,000, with projects settling for far less.3. BMW M78 1.2-liter inline-6BMWBMW might not have invented the inline-6 engine, but the German brand sure has made good use of them throughout its history, delivering some real greats like the S54 and S58. Long before those powerhouses arrived, though, BMW blessed buyers in 1933 and 1934 with the M78 — its first inline-6.AdvertisementAdvertisementThis was no thunderous performer, but instead a modest engine designed to give buyers in a more mainstream class of vehicle a level of engineering refinement that had escaped them thus far. The M78 produced a healthy 30 horsepower, which proved enough to propel the 303 Sedan to a top speed of around 55 mph, while returning around 23 miles per gallon. It sported an overhead-valve design, with two valves per cylinder, and the displacement sat at 1,173cc. A pair of Solex carburetors fed the engine, while a four-speed transmission directed the power toward the wheels.BMW's tiny inline-6 was soon replaced by a larger, more capable 1.5-liter unit, with the Bavarian automaker producing only 3,210 303s, with just over half of them sedans. There was never a hot M78, but the importance of these almost century-old cars should not be underestimated. The 303 and its M78 effectively laid the foundations for the six-cylinder recipe that has underpinned BMW for so long.2. ERA 1.1-liter inline-6Goodwood Road & Racing/YouTubeThis isn't a brand you'll find in any showrooms today, as ERA — English Racing Automobiles — is a long-gone but certainly not forgotten racing automaker that produced its last car in 1952. Production of ERAs began in 1934, and throughout the firm's 18-year history, just 20 cars were produced, so these are, and always have been, extremely scarce rarities.These cars were all racers, and they took motivation from Riley-derived inline-6 engines of various displacements. The choice for buyers was a 2.0-liter, 1.5-liter, or — the engine under our spotlight here — a 1.1-liter inline-6. Only a small number of the already diminutive production run were built with the 1.1-liter, or 1,088-cc, mill in place, and even then, those engines were often swapped out in later years for more powerful ones as owners sought enhanced performance from the little racers.AdvertisementAdvertisementIt might seem logical to have purchased a larger-capacity engine from the outset, but budget constraints might have forced some aspirational speed-demons to save some cash and opt for the little 1.1-liter. Reportedly, the smaller-engined models commanded just 1,100 pounds ($5,540) when new in 1934, while 1.5-liter and 2.0-liter cars cost 1,500 pounds ($7,560) and 2,000 pounds ($10,100) respectively.1. MG 1.1-liter inline-6John Keeble/Getty ImagesThe last — and smallest entry — in this collection of dinky six-cylinder engines is again from England, where it would seem small-displacement inline-6s have been a particular specialty. It's a 1,086 or 1,087cc unit (depending on the exact application and engine type) used in early MGs of the 1930s. A variety of models took propulsion from this comically small — by today's standards — inline-6 engine, namely the L-Type and K-Type cars, and, famously, MG's EX135 speed record car.The engine proved quite competitive in competition, with outputs soaring as high as 125 hp in some guises. To achieve such heady figures from such a small engine, MG used superchargers to boost the output, so the little racers were able to achieve speeds in the region of 110 mph, with the first 75 mph reached within 14.6 seconds. Road-going L-Type cars were less capable, but could still reach respectable top speeds in the region of 75 mph.As for the icy cool land speed record car, that's a different story indeed. All of its mechanical components were tucked beneath a wonderfully aerodynamic body, and feeding the 1,087cc lump was a comparatively huge Zoller supercharger. Output here swelled to almost 200 horsepower, and with a long enough straight (and brave enough driver), the EX135 could crack speeds north of 200 mph — all the way back in 1939. It was the first car with an engine under 1.1 liters in displacement to crack 200 mph.AdvertisementAdvertisementWant more like this? Join the Jalopnik newsletter to get the latest auto news sent straight to your inbox, and follow us or add us as a preferred search source on Google.Read the original article on Jalopnik.