Many people prefer buying used cars over new ones because they're vastly cheaper, and more often than not, give you more value for your money than a new one would. But then again, used cars seldom come with warranties from the manufacturers, and because they're a bit older, it usually means their engines are more fragile than they once were.

The following 10 cars we'll be discussing all come equipped with 12-cylinder engines, but they're not recommended to buy in today's day and age. Some of them are made by brands most enthusiasts lust after, and the kings of luxury build some, but we recommend none to one of you, unless you have a thick wallet, and enjoy paying your mechanic a visit every single other day.

10 1995 Jaguar XJS

Jaguar-XJS-via-british-gq
Via British GQ

The Jaguar XJS is what Doug DeMuro referred to as "the cheapest V12 sports car on earth", and once you see that used models are selling for as low as $5,000 on CarGurus to this day, it's to easy to see why. By no means was the XJS a bad sports car, after all, it had a luxurious interior, a timeless elongated design, and a 5.3-liter naturally-aspirated V12 under its hood good for 291 hp.

Jaguar XJS
Via classicautomall.com

But the nail in the coffin for Jaguar's sports grand tourer was its reliability, and as a result, these cars are extraordinarily cheap and cost a fortune to keep running - and did we mention the XJS was one of the spawn created by Ford taking over Jaguar?

9 1999 Aston Martin DB7

1994 Aston Martin DB7
Via Aston Martin

Ironically enough, the aforementioned Jaguar XJS and this Aston Martin DB7 shared many similarities. The problems with the DB7 however aren't only related to its 420-hp V12 powertrain, however.

aston-martin_db7_rear_green
Aston Martin

Because Aston used many expensive materials to carve the DB7 to life, like aluminum, its body was painfully expensive to fix, and even the slightest repairs like brake discs and cracked exhaust manifolds were more expensive than the Jag. It was worth noting that the Aston was also offered with a six-cylinder engine too if you wanted to dodge any V12 maintenance costs.

Related: Best Features Of The 1994 Aston Martin DB7

8 2002 BMW E65 7-Series

2005 BMW 7 Series E65 - front quarter
Via: BMW

The infamous E65 7-Series was designed by the one-and-only Chris Bangle, whether you like his design or not is up to personal preference, but the car as a whole couldn't hold its own over the years. Like many other European luxury cars, the 7-Series was groundbreaking when it first was unveiled with magnificent technological advancements like its iDrive system and adaptive headlights, but over the course of about two decades, these systems start to malfunction more often than not.

The rear of the E65 7 Series
BMW

In the 760i model, the 7-Series was equipped with a 6.0-liter V12 that produced 440 hp and 443 lb-ft of torque; and even this engine was constructed so only the most talented of mechanics could work on it. In other words, when new, the E65 was a great buy, but after some wear and tear, avoid it at all costs.

Related: Every BMW 7 Series Generation, Ranked Worst To Best

7 2009 Audi Q7 V12 TDI

Via: periodismodelmotor
Via: periodismodelmotor

Yep, that's right, once upon a time, Audi pushed the boundaries of diesel power, and allowed its diesel-driven Q7 SUV to inhabit a V12 engine - a 6.0-liter twin-turbocharged one that emitted 490 hp and a whopping 783 lb-ft of torque! This meant that from a stop, the Q7 could reach 60 mph in just 5.5 seconds despite weighing 5,900 lbs, this truly was an engineering marvel.

Rear 3/4 view of the Q7 V12 TDI
Audi

And to be completely frank with you, till this day there never was a car as absurdly brilliant as the Audi Q7 with its V12 diesel engine, but there is one glaring flaw with this vehicle in today's day and age... and it all comes down to how much it'll cost to fill up this bad boy with its MPG ratings of 25 on the highway and 16 in the city.

Related: The Audi Q7 V12 Is The Pinnacle Of The Dirty, Torquey Diesel Era

6 1989 Ferrari Testarossa

Ferrari Testarossa - Front
Via Mecum Auctions

On paper, the Testarossa sounds immaculate, and in the flesh, it's just as beautiful as it looks in the photos, if not even more - but this is one Ferrari you need to stay away from unless you're an ungodly rich avid collector. Contrary to popular belief, the Testarossa isn't powered by a V12 engine, but rather a sublime naturally-aspirated 4.9-liter flat-12 one. If you find one in pristine condition that was preserved by a collector, chances are you won't run into any problems except excessive carbon build-up, but if you happen to come across a tempting high mileage (we use that term very loosely) stay away.

Rear 3/4 view of a red Testarossa, studio shot
Ferrari

Those Testarossas that have been driven hard, or might have encountered a clutch drop or two are bound to have expensive problems arise with their differentials and so-called tune-ups... and of course, some older Testarossas might be deemed completely illegal depending on how your state's laws.

5 2016 Mercedes-Benz G 65 AMG

Silver Mercedes-Benz G65 AMG Parked Front 3/4 View
driving.co.uk

The latest-generation G-Class is an incredible vehicle and completely redefined what the G-Wagon was, although it might not look like it based on first impressions alone. However, the previous-generation G-Wagon was almost an exact carbon copy of all its ancestors that came before.

Black G65 AMG on the road
caricos.com

The sole fact that set the G 65 apart from all other G-Classes however, was what was cooking underneath its hood, a 6.0-liter 600-hp twin-turbo V12, but even that surplus of power couldn't make up for its other drawbacks. That generation of the G-Class wasn't well-built, it was outdated, had an incomprehensible amount of blind spots and body roll - don't forget the insane maintenance costs as well.

4 2002 Mercedes-Benz S600

Black 2001 Mercedes-Benz S600 Parked Front 3/4 View
Via Bring a Trailer

Driving an S-Class symbolizes wealth and class, and for most people, that's all they want, but there's a big difference between driving an S-Class and owning one, especially one with 12 cylinders under its hood. The W220-generation S-Class seems like too good a deal to be true, and well... it is.

Mercedes S600 W220
Via: OldBenz YouTube

See, its 5.8-liter 362-hp V12 might be enough to catapult you to 60 mph from a standstill in just 5.4 seconds, but it can declare you bankrupt even faster. According to klipnik.com the S600's V12 suffered too much power actually; worst-case scenario, the cylinder walls can deform and cause oil to flow into the combustion chamber causing the entire engine to be replaced.

Related: Listen To The Mercedes-AMG One On Track Scream Like Lewis Hamilton's F1 Car

3 1974 Jaguar XK-E V12 Series III

1974 Jaguar XK-E V12 Series III
Via Steve's European Automotive

For this entry, we have almost nothing to critique Jaguar on its reliability, this is just purely based on its design. The Jaguar E-Type was, and still is, one of the most beautiful cars to ever exist, and as its generations evolved, it got slightly less pretty each and every time, and they even added four seats at one point which truly was dishonorable, but the worst out of the bunch was the XK-E Series III.

Silver 1974 Jaguar XK-E V12 Series III Rear 3/4 View
Via JaguarForSale

It might have still come with a 240-hp V12 under its massive hood, but on the outside, it looked like a knock-off of the legendary E-Type, and for anyone who has ever thought of buying a Series III we have one thing to say - don't, just get an order, better, E-Type.

2 1996 Jaguar XJ12L

1994 Green Jaguar XJ12 Parked Front 3/4 View
via Classic Cars

There's a good reason this luxury limousine with a V12 hiding under its hood costs less than $10,000 on Hemmings, and it's not just because of Euro cars' characteristic depreciation. See, the Jaguar XJ12 featured the same V12 found in the XJS, so of course, that meant it came with the same flaws of it and the excruciating repair bills associated with it too.

Purple Jaguar XJ 12 Front 3/4 View Parked
via keoneus

The late '90s XJL was an exquisite luxury sedan, especially the performance-orientated XJR version, but the V12 engine associated with it was just too problematic in the long run, unfortunately.

1 2003 Aston Martin V12 Vanquish

Front 3/4 view of the original Aston Martin Vanquish
mecum.com

The first-generation V12 Vanquish was a sublime-looking car, and because it was driven by James Bond himself in the film, Die Another Day, it earned legendary status almost immediately; its 5.9-liter 460-hp V12 was just the cherry on the cake. Let's address the elephant in the room immediately, buying a used Aston Martin might seem like a sweet deal, but this usually involved a bitter ownership experience, and the V12 Vanquish is a testimony thereof.

Aston Martin V12 Vanquish
Via Marino Performance Cars

Because its V12 produced more than 450 hp - which was much more than Aston was ready for, its transmission was prone to deteriorate rather quickly, especially its clutch, and of course because it was the early 2000s, many of its technology was prone to malfunction, and that also costs quite a pretty penny to repair.