## Current Rotary Engine Cars: A Comprehensive Guide
### Introduction
The rotary engine, also known as the Wankel engine, is a unique type of internal combustion engine that differs significantly from the traditional piston-cylinder design. Invented by German engineer Felix Wankel in the mid-20th century, the rotary engine has fascinated engineers and enthusiasts alike due to its compact size, lightweight construction, and smooth operation.
For decades, the rotary engine has been associated with the iconic Mazda RX series of sports cars. However, in recent years, the production of rotary engine vehicles has declined dramatically. As of today, there are only a handful of current production cars that still use this unique powerplant.
### Mazda RX-8
The Mazda RX-8 is the last remaining production car to feature a rotary engine. Introduced in 2003, the RX-8 is a compact sports coupe that combines a powerful rotary engine with nimble handling and stylish design.
The Renesis rotary engine in the RX-8 produces 232 horsepower and 159 lb-ft of torque. It is paired with a six-speed manual transmission or a four-speed automatic transmission. Despite its compact size, the RX-8 is surprisingly spacious and comfortable for four passengers.
Production of the Mazda RX-8 ended in 2012, making it a rare and sought-after collector’s item. However, the legacy of the rotary engine lives on in the RX-8, a testament to Mazda’s engineering prowess.
### Alternative Approaches
While the Mazda RX-8 is the only current production car with a rotary engine, there have been other attempts to revive the technology in recent years.
**Kawasaki Ninja H2R:** In 2015, Kawasaki unveiled the Ninja H2R, a supercharged motorcycle that uses a supercharged 998cc rotary engine. The H2R produces an astonishing 310 horsepower and 165 lb-ft of torque, making it one of the most powerful production motorcycles ever created.
**Arevo 3D-Printed Car:** In 2018, Arevo, a California-based company, showcased a prototype of a 3D-printed car that featured a rotary engine. The Arevo car is designed to be lightweight, efficient, and affordable, and the rotary engine is seen as a potential solution to these challenges.
### Advantages of Rotary Engines
The rotary engine offers several advantages over traditional piston-cylinder engines:
* **Compact Size:** Rotary engines are significantly smaller and lighter than piston engines of comparable power output. This makes them ideal for applications where space and weight are critical, such as motorcycles and small sports cars.
* **Smooth Operation:** Rotary engines have no reciprocating mass, which means they operate very smoothly and with minimal vibration. This results in a more refined and pleasant driving experience.
* **High Specific Power:** Rotary engines can produce higher power output per unit volume than piston engines. This is because they have three combustion chambers per rotor, compared to one combustion chamber per cylinder in a piston engine.
* **Reliability:** Properly maintained rotary engines can be just as reliable as piston engines. However, they require more specialized maintenance and servicing due to their unique design.
### Disadvantages of Rotary Engines
Despite their advantages, rotary engines also have some disadvantages:
* **Fuel Economy:** Rotary engines tend to consume more fuel than piston engines of comparable power output. This is because the rotary design has inherent inefficiencies, such as heat loss through the apex seals.
* **Emissions:** Rotary engines produce more emissions than piston engines, especially hydrocarbons and nitrogen oxides. This is due to the presence of oil in the combustion chamber, which can burn incompletely and produce emissions.
* **Complexity:** Rotary engines are more complex to manufacture and maintain than piston engines. This results in higher production costs and potential reliability issues.
### Future of Rotary Engines
The future of rotary engines is uncertain. While the Mazda RX-8 is no longer in production, Mazda has expressed interest in developing a new rotary engine for future vehicles. Additionally, companies like Arevo are exploring the potential of 3D printing to make rotary engines more affordable and efficient.
However, it is also important to acknowledge the challenges facing rotary engines. Fuel economy and emissions regulations pose significant hurdles for the technology, and the high production costs make it difficult for rotary engines to compete with traditional piston engines.
### Conclusion
The rotary engine remains an intriguing and captivating powerplant. Its unique design offers several advantages, such as compact size, smooth operation, and high specific power. However, disadvantages such as fuel economy, emissions, and complexity have limited its widespread adoption.
As the automotive industry transitions towards electrification, the future of rotary engines remains unclear. However, the legacy of the Mazda RX-8 and the ongoing efforts of companies like Arevo suggest that the spirit of the rotary engine may live on in some form.
