A car is one of the most complicated machines a consumer can and will buy. With thousands of parts to account for, millions and millions of dollars are spent on engineering a car that actually works, and making it work well.

While engineering is a complex task, its results are mostly understood as an objective factor. If a car is fast, that's undeniable, but under the skin engineering is one thing, designing the aesthetics is another. While mostly subjective, a good looking car is easy to spot, and appreciated by most.

Just like the engineering, tons of money goes into perfecting the exterior beauty of a car. Even with the most skilled team though, things can go horribly wrong fast. Just look at all those classics ruined by ugly modifications. All the effort spent on designing a body that will look good can be instantly wasted with just one wrong move.

So, read on to see 10 cars that are beautifully designed, except for one horribly ugly flaw:

10 2021 BMW 4 Series - The Grille

Via Edmunds

A long-running luxury sedan, the BMW 4 Series is a great car that earned its popularity with good looks and superb performance. While the latest update of the 4 series did an excellent job of styling the body and front end, BMW made a controversial decision to enlarge the grille to almost comical proportions. Gone is the classic BMW "Kidney" style grille, and in its place is a ridiculous looking, massive pig nose grille instead, a move that hopefully doesn't pay off - as massive grilles are perhaps the ugliest trend of the decade.

9 1979 Pontiac Firebird Trans-Am - The Headlights

Via Mecum Auctions

The late '70s and early '80s were a terrible time for muscle cars. With the traditional big-block screamers dead and gone, it was up to the smaller pony cars like the Trans-Am to carry Detroit's muscle legacy. While previous years were down on power, the Trans-Am managed to retain the awesome traditional muscle car looks.

Unfortunately, the 1979 facelift replaced the mean-looking front end with some thoroughly hideous headlights, mounted in an even uglier bumper. A shame, as the rest of the car, retained the awesome styling of previous Trans-Ams.

8 2019 Chevrolet Camaro - The Black Bumper Insert

Via Autoblog

One of the modern generation Camaro's strong points has been its integration of retro and modern styling together. While the 6th generation hit a strong point in the 2018 model year, the 2019 facelift practically ruined it. The large grille isn't too terrible, but the bumper insert painted black to match the grille just makes it look strange and rather ugly. Fortunately, Chevy realized their mistake and fixed it for the 2020 Camaro.

7 1994-96 Ferrari 512M - The Grille

Via Autoevolution

The king of '80s supercars, the Ferrari Testarossa represented the peak of angular wedge-shaped cars.

But, come the '90s, Ferrari began to change up the styling, resulting in the 512M. While it kept the Testarossa's awesome body lines, the front end became a far cry from the aggressive design that defined it previously. Instead, the grille became a dopey smile looking affair that ruined the front end looks. The headlights aren't the best looking, but they pale in comparison to how much damage the grille did to the legendary car's looks.

RELATED: 15 Ugly Cars That Are Much Faster Than They Look

6 2013 Aston Martin DBS Zagato Coupe - The Headlights

Via Pinterest

Hearing the words "Aston Martin" and "Zagato" in the same sentence is bound to indicate a jaw-droppingly gorgeous and sporty car imbued with luxury. While most of that is true for the 2013 DBS Zagato, the sleek design hits a major problem when it gets to the headlights. Instead of accentuating the incredible body, the headlights instead make the front end look like a sad whale, a shame considering how beautiful the rest of it is.

5 Plymouth Prowler - The Front Bumper "Mustache"

Via Bring A Trailer

A legendary oddity and the last dying breath of Plymouth, the Prowler was an awesome idea that had some rather unfortunate execution. Flaws like a Chrysler parts-bin interior and lack of V8 aside, the body of the Prowler is an excellent attempt at making a modern Hot-Rod. That is until you get to the bumper. Unfortunately, those sharp angles up front just wouldn't fly with safety regulations, and the Prowler was bestowed a, frankly hideous, plastic "mustache" bumper that ruined the classic look of the front end.

RELATED: 15 Ugly Cars That Are Actually Incredible

4 1992-95 Dodge Viper - The Soft Top

Via Wikimedia Commons

If you know about the Dodge Viper, you probably know how brutally unrefined the first generation was.

As the hallmark of the Viper, violent levels of power and performance were prioritized, with everything else being an afterthought. While that makes the Viper a special car, it also makes some aspects of it rather ugly. Especially so, the first generation Viper came with a soft top that was absolutely hideous. Looking like a bad toupee, there's a good reason most first-gen Vipers are seen either with an optional hard-top or without a top altogether

3 1997-2004 Porsche 911 Carrera - The Headlights

Via Lot-Art.com

By far the most hated version of the Porsche 911, the 996 generation was faithful to the Carrera's evolution in every way, except for the headlights (and water-cooling, but that's another argument in itself).

Breaking away from the traditional round headlights 911s are known for, the "runny-egg" style headlights became a point of contention for Porsche fans. While not the ugliest headlights in existence, they just don't work well with the 911's gorgeous and sleek body lines. Although the 996 is still a proper 911, and really doesn't deserve to be so hated just because of some ugly headlights - but make no mistake, they are indeed ugly.

RELATED: 15 Worst Car Facelifts That Never Should Have Happened

2 1974 Jaguar E-Type - Safety Bumpers

Via CLASSIC.com

A problem that many cars sold in the USA had to tackle, 1974 saw the introduction of "Safety Bumper" mandates in America. You may have noticed them on 70's classics before - the big ugly pieces of plastic mounted on otherwise gorgeous cars.

Plenty of designs were ruined, but perhaps the worst offender was the Jaguar E-Type. A gorgeously designed car with properly thought out proportions and body lines, Jaguar treated the new bumpers as an afterthought, simply slapping on a couple blocks of plastic to the front end. They're so poorly designed on the E-Type that they don't even look all that safe, and ruin the front end looks with their blocky design.

1 2009-15 Porsche Panamera - The Trunk

Via Car and Driver

Porsche's take on a touring sedan, the Panamera is a great car, in terms of practicality, performance, and luxury.

The problem was, the first generation's rear end was horrendously ugly thanks to the trunk design. Sloped to fit as much cargo as possible, the bloated design just clashes with the otherwise sleek styling - while it does allow for more cargo, it's just plain ugly. Fortunately, though, Porsche corrected this design flaw with the latest generation of Panamera, making it as sleek as the rest of the car, and it looks so much better because of this change.

NEXT: Ugly Ducklings: 10 Cars That Were Unloved When New, But Are Appreciated Today