Who needs a V6 when you could have a V8?
In an effort to be more efficient, the all-new 2020 Audi S6 has dropped the V8 in favor of a V6. Fans of Audi's 4.0-liter V8 may not be happy to hear this news but it isn't all bad. The 2.9-liter twin-turbo V6 Audi has picked for the S6 is the same one used in the RS5 and Porsche Panamera. Here it produces 444 horsepower and 443 lb-ft of torque with the help of a 48-V mild-hybrid system.
Yes, this is a tad less than the old, V8-powered S6 but it is more powerful the diesel model sold in Europe. Pricing starts at $73,900, which is, frankly a lot of money. But we have rounded up six cheaper sports sedans on the used market, all of which offer similar performance to the new S6. All but one has a V8 engine and since the S6 does not compete with the M5s and AMGs of the world, we've resisted the urge to include these types of sedans here.
If you lament the change from a V8 to a V6, just opt for the older C7 generation S6 (sold from 2013 to 2018). It packs a 4.0-liter twin-turbo V8 producing 420 horsepower (or 450 hp in later versions) going out to Quattro all-wheel-drive through a seven-speed DSG transmission. Pricing for used Audi S6 starts in the low $20,000 range but to get a nice example with a CPO warranty, expect to spend within the mid-$30,000 range. You will miss out on some of Audi's latest interior tech but you'll be getting that sweet V8.
The closest competitor to the Audi S6 is the BMW 5 Series, specifically the 550i. This is the V8 model positioned just below the M5 in the range. We recommend the F10 generation because it still has modern technology and has now become very affordable on the used market. All 550i models are powered by a 4.4-liter twin-turbo V8 producing between 402 and 444 hp going out the RWD or AWD. Prices for high-mileage examples are as low as $10,000 and a CPO example can be found under $30,000.
The Audi S6 has always been a quick car but in terms of driving enjoyment, it plays second fiddle to cars like the 5 Series and our next choice, the Lexus GS F. The GS F is the most aggressive version of Lexus' mid-size sedan, using the company's lovely 5.0-liter naturally aspirated V8 producing 467 hp. Used examples start around $45,000 and the GS F will likely be the most reliable car on this list.
The Infiniti M56 (now known as the Q70) is a bit of an oddball on this list because it often goes overlooked among the mid-size luxury sedans. We think the M56 is the prettiest car on this list and it also holds its own in terms of power with a 5.6-liter V8 dishing out 420 hp going out through a seven-speed automatic. Pricing on a used M56 starts around $25,000 or around $40,000 for a newer Q70.
We've already gone on record saying the Kia K900 (and its corporate sibling, the Hyundai Equus) is one of the best, used values on the market. A brand-new K900 still won't cost as much as a new S6 but a used example is an even better bargain. You can now find a CPO K900 with the 5.0-liter V8 producing 420 hp for under $25,000. If there is a more luxurious package available at this price (with a warranty), we haven't seen it.
The Cadillac CTS V-Sport is the only sedan on this list without a V8, though you could easily find a supercharged CTS-V for less than the price of a new S6 if you really wanted. But the V-Sport model is more than what most people need courtesy of its 3.6-liter twin-turbo V6 producing 420 hp and it also offers better value. Used pricing starts at under $20,000, while CPO examples start at just over $30,000. The CTS was based on GM's Alpha platform, making it one of the best-handling cars on this list.