Car manufacturers often tease the release of upcoming vehicles to increase public awareness and help sell their brand. However, some concept vehicles never make it to consumers.

While there may be some initial hype around certain models, problems with the production cycle or poor sales forecasts can lead to manufacturers shelving the models. Here are three concept cars that never made it to the public.

Cadillac Ciel

In 2011, Cadillac introduced its hybrid Ciel to consumers. With 425 hp, a 3.6 liter V6, and twin turbochargers, the vehicle could reach 174 mph. Cadillac originally intended the vehicle to provide a long-distance hybrid solution. Unfortunately, at $300,000, it was more of a luxury vehicle than something that the general public would want.

The company couldn't find the right niche to market the vehicle. While it was well received for its traditional Cadillac-style luxury, it never reached the market because there wasn't enough consumer demand.

Lamborghini Estoque

With 556 hp and a 7-speed dual-clutch transmission, the Lamborghini Estoque was truly something special. Created in 2008, the four-door sedan embodies the company's taste. It boasted a front engine, large wheels, and a solid color design, giving it a striking look. The vehicle could reach a top speed of 208 mph and offered excellent performance and versatility.

However, the project ran short of funding, forcing the company to shelve the design before production could get started. So while there may not be many full-size models in existence, you can still find a Lamborghini scale model of the Estoque for your diecast collection.

Mercedes-Benz Ener-G-Force

Mercedes-Benz produced the Ener-G-Force as an alternative fuel-cell vehicle that runs on hydrogen. With a range of 500 miles, the vehicle would have transformed the green vehicle market, but it couldn't find enough buyers to get off the ground.

Mercedes-Benz designed the Ener-G-Force to take the lead in the fuel-cell market. The vehicle was meant for highway law enforcement use in the United States, but a lack of infrastructure and consumer interest caused the company to pull the plug on production.

Avoiding the Hazards of Production

Today's biggest vehicle manufacturers are searching for the next generation of designs that will improve efficiency and reduce costs. However, on the way, they often create products that don't quite meet the needs of consumers.

Still, there's a lot of value in rare or hard-to-find vehicles. Looking at some concept cars that never made it to the public will give you an idea of what to pay attention to when searching for something unique.