BMW 3.0L I6 Quad-Turbo DieselYes, you read that correctly. At one point, BMW actually made a quad-turbo diesel engine. It's only natural that such a strange creation would make its way onto a list like this. The engine was known as the BMW B57, and, as with most engines, there were a few variants. It's also one of the more modern engines on the list. BMW started putting it in cars in 2016, and it actually did well enough to leave it in the lineup for a number of years. The most powerful version of the B57 was the B57D30S0, which produced 394 horsepower and 561 lb-ft of torque. BMW also included a 48-volt mild hybrid starter generator to reduce turbo lag. It worked, and despite its weird quad-turbo setup, the engine is considered reasonably reliable. It's also fairly fuel efficient, achieving roughly 5.5 liters per 100 km, which loosely translates to around 42 MPG. Since multiple variants of this engine exist, there is a long list of cars in which it was installed. For the B57D30S0, which was the only version with quad-turbo, the models included the G11, G30, G05, G06, and G07. The story of the B57 is a tale of multiple engines. BMW used the quad-turbo version until the pandemic hit in 2020 and then ceased production. However, the twin-turbo B57D30T0 and the single-turbo B57D30O0 are still largely in use today in about a half dozen models each. Maybe they'll bring back the quad-turbo someday.Cummins 6.7L ISBe Turbo DieselThe Cummins 6.7-liter turbo diesel is the current champion of the Cummins lineup. It came to life in 2007 and is still made to this day. Like every other diesel engine maker, Cummins had to come up with something new to counter the emissions standards coming into effect in 2007. Cummins isn't known for releasing new engines very often. The ISBe's predecessor, the 5.9-liter ISB, lived from 1998 to 2007, and its predecessor lasted for 10 years before that. That makes this 6.7-liter turbo diesel the longest-running of Cummins' modern engines at 18 years and counting. Much like the Mack E7, Cummins farms out its engines to a lot of industries, but the strongest one we found made 420 horsepower and 1,075 lb-ft of torque. This particular engine is most commonly found in Ram trucks, namely the Ram 2500 (and higher). With its powerful diesel engine, the Ram 2500 can tow up to 20,000 pounds with a 4,000-pound payload capacity. That is a little over 2,000 pounds more than it can tow with the optional 6.4-liter Hemi V8.Cummins doesn't appear to be stopping this train anytime soon. There is no word on a fresh new diesel coming down the line. Instead, Cummins seems content with iterating and improving its current engine. It makes sense. It's one of the strongest consumer-oriented diesels on the market, so there's no reason to change it up too much right now. GM 6.6L L5P Duramax V8 Turbo DieselWe promised we would get to GM's L5P later, and now here it is. GM brought this 6.6-liter V8 diesel engine into existence in 2017. Back then, the engine was capable of 445 horsepower and 910 lb-ft of torque, which is exceptionally good for a pickup engine. GM did some sort of voodoo because its towing capacity was a staggering 35,500 pounds, second only to Ford in the tow ratings. GM made that version of the engine until 2023. From 2023 onward, a revision to the engine bumped up its numbers pretty dramatically to 470 horsepower and 975 lb-ft of torque. It's not quite as much as the Cummins, but nearly 1,000 lb-ft is still quite powerful. Much like the prior engines, these are mostly made for the larger trucks in GM's lineup, including the Silverado HD and Sierra HD. The bump in horsepower and torque allows properly equipped models to tow up to 36,000 pounds, which is simply incredible. For the time being, GM seems content with this engine, and it is currently equipped in the Silverado HD and Sierra HD. Should GM decide to make another diesel, it'll likely outperform this one, but as it stands, GM's main competitors are either a little weaker or a little stronger, putting GM in a pretty good spot. Audi 6.0L V12 TDIThe Audi 6.0L V12 TDI is the final engine on this list to go into a car. Everything after this is for truck use only. This one also has quite the pedigree. It's been to the 24 Hours at Le Mans, an event that Audi has been dominating since the turn of the century, with 13 wins in the top class since the year 2000. Audi also puts it in its cars and SUVs for the sake of extravagance, since there is no reasonable cause to put a V12 engine into anything designed to get groceries or take the kids to school. Audi made this engine from 2009 to 2012.Let's start with the power figures. The Audi V12 TDI gets up to 493 horsepower and 737 lb-ft of torque, making it one of the strongest consumer-oriented diesel engines ever. The only consumer vehicle to ever have it was the Q7, and all of those come with all-wheel drive. Compared to many of the diesels on this list, this thing chugs fuel at around 21 MPG combined with as low as 16 MPG in the city. Audi has stashed this thing in its Q7, an SUV that can achieve 0 to 60 MPH in under 5.5 seconds. Its theoretical top speed is 171 MPH. Audi deserves some credit for its diesel engines. The automaker was the first to win a 24 Hours at Le Mans with a diesel engine, and the V12 was born out of that success. However, in a Q7, you won't be taking it to the track.