Car nuts seem to be particularly fond of engines with eight or more cylinders, from mean American V8s to screaming twelve-cylinders found in various Lambos or Ferraris. Indeed, their raw power and engineering complexity is genuinely fascinating, often accompanied by soundtracks that would make any enthusiast weak at the knees. But their six-cylinder relatives are pretty sweet, as well, and there are many cult classic icons out there with this engine layout under the hood. That's precisely what we're here to talk about today, more specifically the seven classic inline-sixes hunted by collectors like treasure. Let’s dive in without further ado, shall we? Mercedes-Benz 280SE Average Price: $12,580 Bring a TrailerHere we’re referring specifically to the W108 platform, produced from 1967 up until 1972. The German luxury sedan came with multiple engine options, including a 2.8-liter inline-six known as the M130. It featured a mechanical fuel injection system from Bosch and was capable of mustering 160 horsepower at 5,500 rpm. Moreover, a peak torque output of 177 pound-feet would occur at 4,250 revs, to then be transferred to the rear wheels through either a four-speed manual or an automatic with the same number of gears.The 280SE leans more toward the affordable side than our previous entries, costing around $12,500-$17,000 on average according to Classic.com and The Classic Valuer. But the pricing range is quite broad depending on the vehicle’s mileage and condition, so you might end up paying a lot more for a tidy example. A clean 1970 model went for $25,500 on Bring a Trailer last year, despite having a good 95,000 miles on the clock. Market values have been relatively steady over recent years, though growing collector momentum might lead to them increasing in the future. We can’t know for sure, but it definitely wouldn’t hurt to have such a lovely piece of vintage German luxury in your garage. BMW E30 325i Average Price: $16,764 Bring a TrailerUp next is the legendary E30 generation of the BMW 3 Series, which looks absolutely delicious from every angle. Its boxy design is loved by gearheads of all ages and easily recognizable from a mile away with that quintessential ‘80s flavor, while the engine bay housed Bavaria’s M20B25 powerplant. The 2.5-liter inline-six mill could spawn 168 horsepower and 164 pound-feet of torque, all sent to the rear wheels on the 325i variant of BMW's 3 Series. And because much of this power occurred nice and early in the rev range, it was extremely usable and an absolute blast to experience together with the Bimmer’s balanced chassis.Prices for the E30-gen 3 Series have been trending slightly upward over the last decade or so, and you can expect to pay around $15–20k for a 325i in good shape. There’s no shortage of them, either, so you’ll constantly see clean examples popping up on sites like Classic.com or Bring a Trailer. A pristine M-Technic variant might command something closer to 40 grand, so don’t expect to always get away with spending half that amount. Case in point, an engine-swapped 1989 325i M-Technic raked in a respectable $38,500 on Bring a Trailer just a few days ago. Folks are increasingly drawn to its analog character and timeless aesthetic, which explains why prices are surging in an automotive world full of electronic interferences. Toyota Supra Mk3 Average Price: $20,723 Bring a TrailerThe third-gen Supra (dubbed A70) landed in 1986, with U.S. models powered by a naturally aspirated three-liter mill known as the 7M-GE. It had 200 horsepower and 196 pound-feet of twisting force to play with, but things got even spicier when it came to the turbocharged three-liter made optional in 1987. This bad boy came with 232 horses and 254 pound-feet of torque, enabling the turbo Supra to hit a top speed north of 150 mph. The naturally aspirated version was no slouch, either, as it was capable of reaching 137 mph and going from zero to 60 mph in around seven seconds.Whereas the later Mk4 Supra will set you back a small fortune, the A70 is far more accessible at least for the time being. One could get a naturally aspirated Mk3 for $10,000-$15,000, while turbocharged variants demand a pretty big premium at over 20 grand. For instance, a couple of neat Turbo examples were sold on Bring a Trailer earlier this year for $20,000 and $20,500, respectively. But still, that’s far less than you would pay for the iconic Mk4, which costs around $100,000 in turbocharged form and something in the neighborhood of $50k without forced induction. Third-gen models are an absolute bargain by comparison, still providing a fantastic driving experience for JDM enthusiasts but without costing an arm and a leg. Datsun 240Z Average Price: $36,282 Bring a TrailerOur next entry is a true icon of JDM culture and the starting point to one of Nissan’s most successful lineups, released back when Americans still knew the company as Datsun. Of course, we’re talking about the Datsun 240Z introduced in 1969, with a 2.4-liter inline-six (codenamed L24) residing under the hood. It flexed 151 horsepower and 146 pound-feet of torque, once again channeled to a rear-wheel-drive configuration through either a four-speed manual or a three-speed automatic. Things were unapologetically sporty from a visual standpoint, as well, while the model’s low weight and sophisticated suspension made handling extremely responsive.The 240Z has garnered a sizable cult following over time, and today you’d be paying approximately $35,000 to get one in excellent condition. Prices ballooned during the 2010s but have since been quite steady, but you will still come across a few outliers here and there. Most notably, a 1971 model with low mileage and single-family ownership went for an eye-watering $310,000 on Bring a Trailer back in 2020, and it’s not unheard of for other pristine specimens to command north of 100 grand. That is often the case with concours-level gems meticulously restored back to perfection, so the 240Z clearly has great potential as a collector’s treasure. Austin-Healey 3000 Average Price: $44,060 Bring a TrailerProduced between 1959 and 1967, the Austin-Healey 3000 is one of those lesser-known automotive gems from Britain packed full of classic charm. The model packed a BMC C-Series powerplant displacing 2.9 liters, with its output ranging from 124 to 148 ponies depending on the model-year. Torque sat between 165 and 175 pound-feet, while the top speed of a Mark I variant was rated at 113 mph. At the other end of the spectrum, you had the later Mark III capable of hitting 122 mph when pushed to the absolute limit. All that aside, the car is quite simply a beautiful sight to behold.Based on data from Classic.com, Austin-Healey 3000s are changing hands on the second-hand market for $44k on average. The price range is quite vast, though, so you’ll regularly see mint-condition specimens commanding way more cash. In fact, Classic.com states that the highest recorded sale fetched a whopping $585,000 for a 1967 Austin-Healey 3000 Mark III in June 2025, which is truly off the charts! But most of them go for less than $100,000, while beaters or project cars may cost less than $20,000 depending on their actual condition. Jaguar XK150 Average Price: $82,200 Bring a TrailerWe’re staying in Britain and the same era for this one, it being the Jaguar XK150 produced between 1957 and 1961. The vintage sports car is a majestic display of British elegance at its finest, but it also packs a pretty serious punch thanks to its 3.4- and 3.8-liter mills. On the one hand, the former has between 190 and 250 ponies at its disposal, while the latter ranges from 220 to 265 horses depending on the trim. A 3.8-liter S version boasted a top speed of around 135 mph, and it could fly from zero to 60 mph in just over seven seconds.On average, buyers are spending something in the neighborhood of $80k for this prestigious classic, though values tend to vary significantly based on trim levels and body styles. One end of the spectrum holds the standard fixed head coupe variants at about 70 grand, whereas an S variant with 3.8 liters in the engine bay might fetch as much as $150,000 or more. At a Gooding Christie's auction in 2025, for example, we saw a 3.4-liter S model going under the hammer for $151,200. Prices have experienced a little correction as of late, making the XK150 more accessible to a wider range of potential buyers, at least for the time being. Aston Martin DB6 Average Price: $241,985 Bring a TrailerNow, we’re really entering exotic territory with the final entry on today’s list — the incredibly stylish Aston Martin DB6 released in 1965. It stayed in production until ‘71, defined by its Kamm-style rear end, excellent high-speed stability and unmatched passenger comfort. The engine was a four-liter inline-six boasting 282 ponies and 280 pound-feet of twist, which could launch the DB6 to 60 mph from a standstill in a mere 6.1 seconds. Top speed was rated at a very healthy 148 mph, so the British grand tourer could go fast and look absolutely spectacular doing it.Of course, it’s also far from cheap, with an average price of just over $240,000 listed on Classic.com. A 1967 Volante variant went for as much as $468,000 via Bonhams in October 2025, and the range-topping, 325-horsepower Vantage models are likely to fetch something close to that, too. Clearly, the DB6 is way out of reach for most enthusiasts, and that exclusive nature only adds to its allure. If old-school British goodness is what floats your boat, Aston Martin’s stunner will surely make you weak at the knees.Sources: Classic.com, The Classic Valuer, Bring a Trailer, Gooding Christie's, Bonhams, Hagerty
