Porsche has built a plethora of cool sports cars that fell through the cracks...some of them deservedly so.

Headquartered in Stuttgart, Porsche has been consistent in the development of high-performance sports cars. Prominent nameplates that have worn the Porsche badge include the iconic 911, the Macan, the 918 Spyder, and the Cayman/Boxster. Apart from the well-known models, the star-studded lineup of Porsche cars also includes limited production models and prototypes that never made it to production.

A detailed look at the evolution of Porsche will reveal many mishits, mistakes, successes, and everything in between. Most of the innovative strides taken by the brand sometimes leave behind questionable models that embarrass not only Porsche but also diehard fans. For this list, we're looking at some Porsches everyone has forgotten about and others that were so bad we wish we could forget them.

The 997 Speedster is a special edition that was unveiled at the Paris Auto Salon in 2010 to mark the twenty-fifth anniversary of Porsche's special operations division. Offered as a convertible, the 2-seater Speedster boasts features like cruise control, traction control, stability control, navigation system, and leather seats.

Driving the rear wheels is a rear-mounted 3.8-liter flat-6 engine that pairs with a 7-speed automatic transmission to produce 402 hp and 309 lb-ft of torque. It is capable of running a 4.2-second 0-60 mph and a top speed of 190 mph.

Before the 603 hp Porsche Carrera GT of 2004, there was a 924 Carrera GT that was released in 1980 for Group 4 racing. Further developments led to the creation of more powerful versions. To comply with homologation regulations, 400 road-going GTs were offered.

The turbocharged I-4 engine made 207 hp in the standard GT, 242 hp in the GTS, and 266 hp in the GTS Clubsport. At the top of the food chain is the GTR version, a stripped-out 320-hp beast that is rarely seen since Porsche made only 17 of them.

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The Porsche 911 SC/RS was developed as a road-legal Group B rally car and sold by the race department to selected customers. All 20 units built were finished in white boasting adjustable Bilstein dampers, Spartan interiors trimmed in black felt, and the use of aluminum for various components to save weight.

From the rear end of the car, a 3-liter flat-6 engine cranks out 250 hp and 184 lb-ft of torque to drive the rear wheels. Hooked to a 5-speed manual transmission, it sends the 2330-pound car to 62 mph in 5.3 seconds and a top speed of 158 mph.

With only 11 examples built before the program was discontinued, the Porsche 916 is one of the rarest and most desirable Porsches around. Based on the lightweight Porsche 914, the 916 outperformed other road-going Porsches thanks to an overdose of adrenaline from its 911-sourced big flat-6 engines.

It got a fixed steel roof, wider fenders to accommodate the bigger wheels, 4-wheel ventilated disc brakes, and aerodynamic front and rear bumpers. After considering it too costly to make financial sense, Porsche pulled the plug on the 916 a couple of weeks before its debut at the Paris Auto Salon.

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With only a total of 12,776 cars manufactured in a 5-year production run, the front engine 968 is not one of Porsche's popular models. It is therefore not surprising that its turbocharged variant, with only 14 examples manufactured in 1993, makes it into the list of forgotten models.

The 968 Turbo S is powered by a 3-liter turbocharged engine that produces 305 hp and 369 lb-ft of torque. Routed by a 6-speed manual transmission, it pushes the 2866-pound car to 60 mph in 4.7 seconds and to a top speed of 175 mph.

The Cayenne is a midsize SUV that debuted for the 2003 model year as the first 4-door vehicle from Porsche. Although the whole first-generation lineup is guilty of being a maintenance nightmare, the 2004 model is more notorious than the rest.

NHTSA reports eight recalls for it on issues like faulty seat belt latch attachment bolt, faulty seat belt retractor, and improperly welded driver's seat frame. Others include cracked fuel pump flange, incorrectly routed wiring harness, and fractured transfer case housing that could lead to incorrect torque application.

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Six years after the Porsche 912 was replaced by the Porsche 914, the nameplate was revived for the 1976 model year as the 912E. With the impending demise of the 914, it was Porsche's new entry-level model while the 924 (the 914's official successor) was still being developed.

The major problem with the US-only 912E was that it was grossly underpowered, and Porsche only succeeded in moving about 2100 cars for that single model year. Displacing 2 liters, its 4-cylinder engine could only produce a pathetic 86 hp and 98 lb-ft of torque.

The Porsche 914 is a 2-door Targa top roadster that was developed in a joint venture with Volkswagen as a solution to the Porsche budget problem. Produced primarily with flat-four engines ranging from 1.7 to 2.0 liters, the car was rather slow and yet ended up costing more than originally planned. There was also a rare six-cylinder version whose price was close to that of the entry-level 911, making it a tough sell. In its favor was its go-kart-like handling that made it fun on a curvy road.

Still, the fact that it was originally co-developed by Volkswagen did nothing to help its reputation.

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Replacing the problematic 996 in 2005, the Porsche 997 debuted with several notable changes such as a switch to traditional round headlights, a nicer interior, and a slightly more powerful engine. Despite these changes, the 997 was still technically very similar to the Porsche 996, and unfortunately, it inherited some of the 996's woes.

Most got the Porsche 996's M96 engine which was prone to IMS (Intermediate Shaft) bearing failures, cylinder cracking, and oil leakage from the rear main seal. In addition, the 2005 model is also plagued with valve cover leaks, cam tensioner/timing issues, and persistent leakage of coolant.

Although the 996 performs credibly in terms of speed and handling, it had too many cheap components and build quality issues for a high-priced 911. Co-developed with the entry-level Boxster to save development costs, the two models ended up with interchangeable parts, a move that left 911 purists disappointed.

Furthermore, the water-cooled 3.4-liter engine that supplied power was prone to oil leakage at the rear main seal, loss of coolant, and cylinder head failure. To fix most of these problems required expensive repairs and upgrades at the owner's expense.

Jay Moren is a car enthusiast who loves everything with an engine. When he's not writing about cars, he plays the saxophone and keyboard. He also plays as a goalkeeper for a non-league side in his native Nigeria