The car industry is full of hidden examples of companies stuffing totally inappropriate engines into otherwise sensible cars. Sometimes, they're engines with unusual configurations. Other times, they're torque monsters that are designed for towing heavy loads or to make a statement about how far certain types of engine technology can be pushed. There are also a couple of cases where an engine designed for sports cars has been dropped into something that definitely wasn't originally supposed to besporty, giving birth to some of the coolest sleeper cars for enthusiasts who want to keep a low profile. Whatever the case, these are all outwardly sensible cars that had somewhat less than sensible engine choices. Audi A8 (D3) 6.0-liter W12 (2004-2009) Via: Cars & BidsWhen it comes to luxury sedans, the Audi A8 has to be one of the most sensible and unassuming options around. It's the car of choice for stealth wealth practitioners all over the world. That also means it's the perfect platform to hide a crazy engine that nobody would suspect. In the case of the D3-generation Audi A8, it was the 6.0-liter W12. This engine configuration was made by essentially fusing two VR6 engines together. Its packaging was actually smaller than the 4.2-liter V8 that was also available in this generation of the A8. The A8 W12 had the naturally aspirated version of that engine, which produced 444 bhp and 428 lb-ft of torque. That made it just as powerful and as fast as the V10-engined S8, going from 0-62 in 5.1 seconds and hitting an electronically limited top speed of 155 mph.You can pick up a D3 Audi A8 for around $15,332 these days. The W12-engined versions tend to be around the higher end of this average. That's if you do find one for sale, though. The W12 version of the A8 wasn't a big seller, and people tend to want the S8 more thanks to its glorious V10. But, with the W12 engine now out of production for good, you just might get an edge by buying one of these as an investment. Audi Q7 (Typ 4L) 5.9-liter V12 turbodiesel (2008-2012) On the face of it, the Typ 4L Audi Q7 is a sensible premium family SUV. In fact, that is the reason why most people buy them. They're comfortable, practical, and can be found for decently good money on the secondhand market now. But, not every single version of the first-generation Q7 was the sedate family hauler Audi wants you to think it is. One of the top engine options you could have for this car was a 5.9-liter V12 twin-turbocharged diesel! This engine was born out of Audi's endurance racing program, and it's definitely one of the most insane diesel engines ever offered in a production car. It was by far the most powerful engine option the first-generation Q7 had, producing 493 hp and 738 lb-ft of torque. That makes this the torquiest engine on this list. If you need to do some heavy-duty towing, the Audi Q7 V12 TDI might actually be one of the best options out there.Not many Q7s were made with the V12 diesel. As a result, they can be hard to find on the used market. If you do find one, you can expect to pay anywhere from $34,000-$42,000. You'd have to find that torque monster of an engine incredibly tempting to want to splash out for one of these. Chevrolet Suburban 2500 (Ninth Generation) 8.1-liter V8 (2001-2006) There aren't that many cars out there that are more quintessentially American than the Chevrolet Suburban. That's even more the case when you think of the Suburban 2500. This is a heavy-duty variant of the Suburban, based on the Chevrolet Silverado 2500. As part of this, the 9th-generation Suburban 2500 got an engine option that was pretty crazy for a large family SUV. While it had the same 5.3-liter and 6.0-liter Vortec V8 options as the 1500, it had an 8.1-liter V8 option that was exclusive to it. This massive V8 produced anywhere from 320-340 hp and 440-455 lb-ft of torque. While this only made it marginally more powerful than the 6.0-liter engine, it did have significantly more torque. That makes it the engine of choice for anyone who wants to do a lot of towing with one of these.A 9th-generation Suburban can be yours for around $19,309. Suburban 2500s with the 8.1-liter engine are much more expensive, typically going for $36,000-$45,000. This makes it one of the more expensive options here, and one you'd definitely have to be really serious about wanting to go for. Dodge Durango (WD) 6.2-liter supercharged V8 (2021, 2023-2025) DodgeThe WD generation Dodge Durango is a regular sight on North America's roads. It's a popular family hauler, able to seat up to 7 people and carry plenty of luggage. Most versions of the Durango have the 3.6-liter Pentastar V6 engine. But, for a brief period of time, you could get the Durango with the 6.2-liter supercharged Hellcat V8. This model is known as the Dodge Durango SRT Hellcat, and it's an incredibly underrated performance SUV. Initially only produced for the 2021 model year but then brought back from 2023-2025, the Durango SRT Hellcat has an output of 710 hp and 645 lb-ft of torque. That makes it one of the most powerful cars on this list.Due to its unique qualities as a supercharged high-performance SUV, the Durango SRT Hellcat has become very desirable. That's kept used prices high. You'll need to pay around $93,156 to have one of these, and that value really isn't decreasing that much any time soon. What you do get for that money, though, is something that's unlike almost any other SUV on the planet. It's really an enormous muscle car with 7 seats. There's no way you can argue that won't be good fun. Dodge Ram 1500 (Third Generation) 8.3-liter V10 (2004-2006) 2005 Dodge Ram SRT-10 6-SpeedThe Dodge Ram 1500 has been one of North America's prime workhorse and lifestyle vehicles for a long time. They can be specced as utilitarian work trucks or luxurious family haulers, and everywhere in between. This has included high-performance versions. The third-generation Ram 1500 had perhaps one of the most famous high-performance pickup variants of all time. That's because it was powered by the Dodge Viper's 8.3-liter V10.This was known as the Dodge Ram SRT-10, and it was only built from 2004-2006. The huge V10 produced 510 hp and 525 lb-ft of torque, and could take this pickup from 0-60 in 4.9 seconds. That was staggeringly fast for a pick-up truck of that era, matching the time a brand new Chevrolet Corvette of that era was able to achieve.You can pick up a Dodge Ram SRT-10 for around $41,489 now. That sounds really expensive, but some examples have sold for less than $20,000 or even less than $10,000. If you're lucky, you could end up getting a proper bargain. Ford Excursion 6.8-liter V10 (2000-2005) Bring A TrailerMuch like the Chevrolet Suburban we talked about earlier, the Ford Excursion is a vehicle that couldn't be more typically American if it tried. A direct rival to the Suburban 2500, the Excursion was only ever produced in one generation during the early to mid-'00s. It had several engine options over its lifespan, most of them being diesels. Only two petrol engines were offered, and one of them is one of the most monstrous engines Ford has ever made. Being based on the Ford F-250 medium-duty pick-up truck of the same era, the Excursion also got access to the F-250's 6.8-liter Triton V10. This engine produced 310 hp and 425 lb-ft of torque. While this wasn't the most powerful engine you could get in the Excursion (the 6-liter PowerStroke turbodiesel, which produced 325 hp and 560 lb-ft of torque, was), it was definitely the coolest-sounding one.Excursions tend to go for around $28,879 these days. You can get some examples for less than $10,000, though. If you know where to look, you could get a serious bargain out of one of these V10-engined beasts. Jeep Grand Cherokee (WK2) 6.2-liter supercharged V8 (2018-2021) JeepThe WD generation Dodge Durango wasn't the only Stellantis-built SUV to get a model with the Hellcat engine. The WK2 generation of the Jeep Grand Cherokee also got a model powered by that crazy 6.2-liter supercharged V8. This model is known as the Jeep Grand Cherokee Trackhawk, and like the Dodge Durango SRT Hellcat, it's pretty much an enormous muscle car. This 707 hp monster can accelerate from 0-60 in just 3.5 seconds. That's the same kind of 0-60 time as the BMW M3 Competition from the same era! It can also cut the mustard off-road, thanks to having a sophisticated all-wheel drive system with multiple drive modes and an impressive 8.1 inches of ground clearance.The Jeep Grand Cherokee Trackhawk is easily the most expensive car on this list to buy used. You'll need around $89,088 to buy one, and some examples have sold for over $100,000. What you get for that money, though, is perhaps one of the greatest performance SUVs ever made. Mercedes-Benz R-Class 6.2-liter V8 (2007) 2007 Mercedes-AMG R63The R-Class is a little-known Mercedes-Benz model that was never successful. It was an attempt at making a luxury minivan, and it also had some crossover elements. Its attempt at being a practical daily driver for a large family was also reflected in its fairly sensible engine choices. It had the typical range of petrol and diesel engines you would find in a large Mercedes of the day. None of these were anything to write home about. That is, except the 6.2-liter V8. For one model year only (2007), Mercedes tried selling an AMG version of the R-Class! The R63 AMG had 503 hp and 463 lb-ft of torque, along with all-wheel drive. This gave it a 0-62 time of 4.6 seconds, as well as a top speed of 155 mph (or 171 mph if you chose the optional AMG Driver's Package).Because it was only produced for one model year, you're not very likely to find one on the used market. If you do, you can expect to pay around $34,660 for it. If you want a quirky family car that's got great performance, it might be worth a shot. Volkswagen Passat (B5.5) 4.0-liter W8 (2001-2004) From the outside, you'd be hard-pressed to find anything spectacular about the Volkswagen Passat W8. There are only a few visual differences between it and a regular B5.5 Passat. But, when you look under the skin, this car is one of the weirdest and wildest beasts VW has ever made.Its 4.0-liter W8 engine produced 271 hp and 270 lb-ft of torque. That easily made it the most powerful engine option you could get in the Passat at the time. It was also the fastest Passat of its generation too, with a 0-62 time of 6.8 seconds and a top speed of 155 mph. That fast 0-62 time was partly due to it having VW's 4MOTION all-wheel drive as standard. Volkswagen also seemed to want to make a point that this was a Passat for proper drivers, as you could have it with a 6-speed manual transmission as well as the 5-speed automatic it shared with other B5.5 Passat variants.Why did the Passat even get given this crazy engine option in the first place? The answer is actually pretty simple. Volkswagen wanted to use it as a test bed for the more powerful and exotic W engines. The Passat W8 first hit the market in 2001, a good few years before the W12-engined Volkswagens, Audis, and Bentleys appeared. Putting a smaller version of the W engine with fewer cylinders into a tried and tested platform seemed like a no-brainer at the time. It could see how reliable the W engine concept was in the real world, and also have a look at how popular it was with customers.If you want to get one of these exotic-engined Passats, you won't have to pay very much. The average value of a B5 or B5.5 Passat is around $8,416 these days, with W8-engined versions on the higher end of that average. Some W8s have sold for as much as $22,000, but typically they sell for around the $5,000-10,000 mark. They may not stay that cheap forever, so it might be worth picking one up and investing in it. Volkswagen Touareg (7L) 6.0-liter W12 petrol (2005-2010) And 5.0-liter V10 turbodiesel (2002-2008) 2004 Volkswagen Touareg V10 TDILast but certainly not least, the Volkswagen Touareg is the only car on this list that was offered with not one but two crazy engine choices. At different times, you could have had the first-generation 7L model with either the 6.0-liter W12 petrol engine or the 5.0-liter V10 turbodiesel. The latter of those two choices was perhaps the more fitting one for a big SUV like this. While its 309 bhp meant it was significantly less powerful than the 6.0-liter W12 petrol (which had 444 bhp) and the 4.2-liter V8 petrol (which had 306 bhp), it was the torquiest engine option by far at 553 lb-ft.This is something Volkswagen made sure to advertise in its marketing at the time. V10 TDI-equipped Touaregs were often shown easily pulling massive loads that other cars would have either struggled with or not even been able to budge. In one particularly famous stunt, one of them managed to tow a Boeing 747 airliner. This was filmed for the motoring show Fifth Gear, and it definitely got everyone's attention.Unfortunately, the V10 TDI died a death thanks to not being a big seller and Volkswagen's Dieselgate emissions scandal. But, its use in the otherwise very sensible Touareg has made it a truly legendary engine. They're also not that expensive to buy used. You can expect to pay around $16,108 for one, with some examples selling for as low as $7,300. For something with that much pulling power, that's incredible value for money.Sources: Audi, Chevrolet, classic.com, Dodge, Ford, Jeep, Mercedes-Benz, Volkswagen