Great engines that put six cylinders in a straight line
Okay, so BMW has almost single-handedly kept the straight six alive in cars for the last decade or so, and it continues to make some great inline engines. But with Mercedes-Benz's impending return to straight sixes, we could be on the verge of a resurgence for the I6 format.
In (hopeful) honour of that we present you with our picks for five of the best straight sixes from around the world. Now, we know there are a lot of great ones from history, so we have limited it to the major car-manufacturing continents and the UK, just because they have made so many great ones.
BMW S54 (Europe)
While BMW has made a huge number of truly great inline sixes, the S54 stands out because of its sheer technical innovation and the fact it produces a staggering 265kW of power and 370Nm of torque (in its most powerful version) from a naturally aspirated configuration.
Oh, it also happened to power one of the greatest BMW M3s of all time as well - the E46. With a displacement of 3246cc, the S54 featured BMW's cutting-edge Double VANOS continuously variable valve timing system and, most importantly, sounded utterly magnificent.
TVR Speed Six (UK)
While BMW may have made some pretty impressive straight sixes, it is TVR that actually produced the most powerful naturally aspirated straight six ever fitted to a production vehicle.
The mighty Speed Six produced 302kW in its ultimate 4.0-litre form that featured in the TVR Sagaris, Tuscan S and Typhon and sounded even more magnificent than the S54. TVR further developed the Speed Six into the Speed Twelve by joining two of them on a common crankshaft to produce 700kW. This caused then-owner Peter Wheeler to cancel the Cebera Speed Twelve road car project - because it was simply undriveable as a road car.
Nissan RB26DETT (Asia)
The engine that made the Nissan a legend faced some pretty stiff competition from other Japanese inline sixes, but the fact that it remained as the powerplant in the GT-R in R32, R33 and R34 guises (that's 1989 to 2002) sealed the deal.
The 2.6-litre RB26DETT packed aluminium 24-valve cylinder heads, six individual throttle bodies and pair of ceramic turbochargers. Nissan extensively tweaked and upgraded the RB26DETT over those year, of course, and while Nissan rated the RB26DETT at 206kW, this was only due to the "gentlemen's agreement" between manufacturers to limit advertised power figures to this number. Modified versions easily achieve 375kW, with extreme examples getting as high as 1000kW.
Ford Barra 325T (Australia)
While Ford Australia's 4.0-litre inline six was utterly ancient, the addition of a turbo in 2002 gave it a new lease on life and the final hurrah in the FGX XR6 Turbo was simply sublime.
With nothing left to lose, Ford cranked the Barra turbo up past FPV levels to achieve 325kW of power and 576Nm of torque (the last FPV F6 produced 310kW and 565Nm), with even more on offer with the 10-second overboost - 370kW and 650Nm. Pretty impressive for an engine that can trace its roots all the way back to 1959.
Cummins ISB 6.7 (USA)
Yeah, okay, so Americans are really more all about the V8s, but they have produced a few staggeringly good inline sixes. Mainly diesel truck engines though.
That's exactly what the massive 6.7-litre Cummins diesel in the Ram 2500 and 3500 is.
While its 276kW of power is impressive enough, it is the thoroughly massive 1084Nm of torque that makes the ISB 6.7 truly staggering.
Capable of hauling 6942kg, the huge engine is all about its even more huge torque figure, whether it be lugging that massive load or cruising around town in traffic.