Once in a while, during the perpetual race to be the latest and greatest, a car company will get overly ambitious. Quite often, over-ambition ends in an amazing car, or part of a car, but ends up being too expensive for the car-buying public to swallow. It often ends with an amazing car that's inclined to be unreliable and to be avoided, ending in sales failure and a damaged brand reputation. We think over-ambition is to be celebrated, though. Lessons are learned, and the enthusiast world often gets some fascinating cars to look back on. These are just a few examples.

Volkswagen Phaeton

Volkswagen's attempt to make and sell a high-end luxury sedan is the poster boy for over-ambition in the automotive world. On paper, the car is amazing. It was hand-built primarily in Dresden, Germany, shared a platform with the Bentley Continental GT and Flying Spur, and used engines shared with the Audi A8. Those engines were a choice of a couple of VR6 engines, a 4.2-liter V8, or a massive 6.0-liter W12 engine making 420 horses and 406 lb-ft of torque.

Unfortunately, the Phaeton had several problems that led to failure. The first was its extensive list of electrical gremlins that like to rear their ugly little heads. The second was that it was a $100,000-plus Volkswagen. The Volkswagen group already had luxury brands making luxury vehicles for the super-rich, and Volkswagen's brand identity is literally for building cars for the people. The Phaeton was built between 2002-2016, a surprisingly long run but Volkswagen had committed. Volkswagen sold around 6,000 cars annually, mostly domestically. The European newspaper, The Economist, had it on Europe's biggest loss-making cars while Top Gear Magazine gave it a place on its "The worst cars you can buy right now" list.

BMW M5 (E60)

The V10-powered M5 was best summed up by YouTuber Doug DeMuro when he declared it as "The best car you should never own." It's a startlingly good car to drive, even by M5 standards, and was the first production sedan to use a gasoline-fueled V10 engine. The V10 makes 500 horsepower and sounds and feels spectacular, particularly as it's paired with BMW's SMG-III seven-speed single-clutch transmission. Unfortunately, the V10 is also the car's downfall. It's well known for having rod-bearing failures that can, and will, kill the engine if not addressed. The other weakness is the common failure of the electronic throttle actuators.

BMW built 20,589 models spread between sedan and station wagon body styles over five years. Only 8,800 came to the US, and they were all sedans, but it was still the biggest market for the 2004-2010 generation M5.

Citroen SM

When it comes to ambitious cars that made the grade in everything but price, the Citroen SM is a prime example. It's an incredible car that came about because the French automaker was working on a performance car when it bought Maserati in 1968. The idea was to marry Maserati's high-performance engine technology with Citroen's sophisticated and renowned suspension technology. Citroen also weaved its magic with the brakes to release a luxurious, quick, sharp-handling car that had the shortest stopping distance of its time. Its feature list included hydro-pneumatic self-leveling suspension, self-leveling lights and directional lights, and variable-assist power steering - all ahead of their time in 1970. The SM has since become a cult classic, but at the time, its price and the fact that it required specialist maintenance impacted sales dramatically. Only 12,920 were made, with 2,400 of them coming to America. One of those ended up in Jay Leno's collection, and you can often see it in the background of his garage location YouTube videos.

Cadillac XLR

What if you took the Y platform for the C6 generation Corvette, added Cadillac's excellent Northstar V8, a slick power-retractable hardtop, a luxurious interior, and let the Cadillac designers go to work on the body? On paper, you would have America's answer to the Mercedes SL - a stylish, fast, luxurious roadster with razor-sharp handling. You could even get an XLR-V with a supercharged version of the Northstar V8, making 443 hp for $100,000.

The problem was most cars were expensive and hard to justify next to the German competition, a problem Cadillac still has today. In total, 15,460 were built, with about 3,500 per year in the first year but way below the expected 5,000. It didn't work as a halo car, but it did start Cadillac down the road of competing properly with BMW and Mercedes.

Fisker Karma

When it comes to cautionary tales in the automotive industry of car industry mavericks starting a new company and failing hard, Fisker's isn't as spectacular as, say, DeLorean's. It also made sense on paper as Henrik Fisker, the company's founder, is a car designer and penned one of his finest aesthetics to date to create the Karma. In 2011, plug-in hybrid cars were here to save the planet, and the Prius was selling like crazy. The opportunity to sell a premium plug-in hybrid was there, and Henrik Fisker went for it. His sedan looked more like a supercar, and a shade over 400 hp was generated by two electric motors and a turbocharged Ecotec engine from GM. It cost $102,000 and was well received by the automotive press for its ambition and style. However, it was cramped inside, the 0-60 mph time was only 5.9 seconds, and its top speed was 125 mph. Those weren't $100,000 figures for a car making 400 horsepower, and rich car buyers weren't as interested in fuel economy as expected. A little over 4,000 were sold in the US and Europe during its two-year production run, which ended with the company's bankruptcy in 2013.

Chevrolet Tahoe Hybrid

What class of everyday vehicles would benefit most from a hybrid drivetrain? Big body-on-frame V8-powered SUVs, of course. In 2008, the Chevrolet Tahoe Hybrid was ambitious for two reasons. The first was cultural, as the flag-waving hybrid Prius was generally despised by the sort of people that fetishize the American V8 in trucks and SUVs. Putting a hybrid drivetrain in an all-American SUV was a bold move at the time, and the hybrid version of the Tahoe retained its power, towing capability, and seating for eight. With a lighter aluminum hood, front bumper beam, driveshaft, and rear liftgate to offset some of the additional weight, the Tahoe Hybrid managed 20 mpg city and 23 mpg highway over 14 mpg city/20 mpg highway for the non-hybrid version. America just wasn't ready for it, though, and the Tahoe Hybrid lasted only a year.

Lincoln Blackwood

Lincoln entered the truck market with the intent of selling at least 18,000 units of its exclusive and luxurious truck. The idea was to marry the utility and ruggedness of the Ford F-150 and Lincoln Navigator, with the finishing touch being a wood-paneled cargo bed. The concept featured African blackwood, but that was too expensive for production, and laminate composite panels were used instead. It went on sale for the 2002 model year for $52,000, which would be around $72,000 now. Not crazy money when you see what people are prepared to pay for luxury in a truck now, but in 2002 it was a resounding "Nope!" from US customers while it sold into the 2003 model year in Mexico. Even with the additional year on sale in Mexico, Lincoln only sold 3,356 of the 18,000 it expected to sell in total.