Goodbye econoboxes. Hello green scream machines.

The days of fuel economy only coming in small, slow and stripped-down cars are over. Every major auto show these days brings the unveiling of another green super car using hybrid or electric car technology to conserve fuel while delivering Ferrari-like performance. Do any of these wild concepts have a real shot at becoming cost-effective realities? Not so much. And yet, with each new green racer, the appeal of hybrids and electric cars to mainstream drivers grows a little stronger. Here are our all-time fantasy favorites that could leave the Tesla Roadster and Fisker Karma—two screaming fast and quite real production cars—curled up on the pavement coughing dust.

Let’s not forget that, in the real world, one of the most practical and immediate ways to conserve fuel is to drive at the legal speed limit.

1Shelby Ultimate Aero EV

(Zero-to-60 in 2.5 seconds / 1,000 Horsepower)

Shelby Supercars, the firm that manufactures the world’s fastest production car, unveiled the world’s fastest electric car in January 2009. The Ultimate Aero EV can reach speeds of 208 mph and can accelerate to 60 mph in just 2.5 seconds. It is powered by a twin motor system, producing a staggering 1,000-horsepower and 800 lb-ft of torque. According to Shelby, the Ultimate Aero EV will have a range of between 150 and 200 miles. The manufacturer expects to roll out pre-production versions of the vehicle by June—and then plans to use its technology to produce small and more practical electric cars.

2Namir Hybrid

(Zero-to-62 mpg in 3.5 seconds / 362 Horsepower)

The most recent addition to the green super car club is the Namir Concept, a striking new hybrid supercar developed jointly by Italdesign Giugiaro and the iconic British automotive engineering firm, Fraser-Nash Research. Unveiled at last week’s Geneva Motor Show, the exotic vehicle boasts output of 362 horsepower, a top-speed of 187 miles per hour, and fuel economy as high as 110 miles per gallon. The secret is a hybrid system that utilizes a gas-powered endothermic rotary engine, a 400-volt lithium polymer battery pack, and four electric motors—two at the front axle, two at the rear. And perhaps most importantly, the chassis weighs only 250 pounds. By the way, Namir means ‘tiger’ in Arabic. Very fitting.

3Toyota Alessandro Volta

(Zero-to-60 in Under 4 seconds / 408 Horsepower)

Toyota Alessandro Volta

A collaboration between Toyota, and again, Italdesign Giugiaro, this concept from a few years back bears the name of the iconic physicist and inventor of the battery. Built on a carbon fiber chassis, the sleek three-seater is powered by the same four-wheel-drive hybrid system as the one found in the upcoming Lexus RX 450h—and its predecessor, the RX 400h. The Volta combines a V6 gas engine and two electric motors, one at each axle. Total output is a 408 horsepower, which results in a sub-four second zero-to-60 sprint, and a top-speed of 155 miles per hour.

4Toyota Supra HV-R

(Zero-to-60 in Under 4 seconds / 700 Horsepower)

Toyota Alessandro Volta

Designed by Parisian firm Sacha Lakic, this hybrid racecar feeds power to all four wheels thanks to a 4.5-liter 480-horsepower Super GT V8 engine combined with three electric motors—one at the rear-axle, and two in each of the front-wheels. Total output is a Nascar-like 700 horsepower. Due to a mostly stripped-out interior, the car weighs about 2,400 pounds. The HV-R was the first hybrid racecar ever to win a major racing event when it finished first place at the 616-lap Tokachi 24 in Japan in 2007.

5BMW Formula 1 KERS

(Approximately 750 Horsepower)

BMW Formula 1 KERS

Taking Formula 1 into a more eco-friendly direction, the BMW unveiled the Sauber F1.09 in January 2009. The Sauber team is employing the braking technology called Kinetic Energy Recovery System, or KERS. A kind of high-powered variant of regenerative braking, KERS captures energy created during braking and stores it for use by the hybrid powertrain. The Sauber F1 racecar uses this technology in much the same way standard BMW production vehicles utilize ActiveHybrid technology. BMW hopes to learn more from the F1 experiment in order to make advancements in the consumer market. BMW Sauber still hasn’t decided whether it will race with its kinetic energy recovery system in this year’s season-opening Australian Grand Prix.

6Wrightspeed X1

(Zero-to-60 in About 3 Seconds / 300 Horsepower)

Wrightspeed X1

Built by Ian Wright, a former Tesla engineer, the Wrightspeed X1 is a rear-drive open-wheel roadster outfitted with an all-electric powertrain. The system unites an electric motor from AC Propulsion, lithium ion batteries from A123, and a Honda transmission. Its compact Ariel Atom body features lightweight components and an aerodynamic design. The Atom was the perfect candidate due to its lightweight and efficient design. The little racer attracted a lot of attention when it entered a drag race and beat out a Porsche Carrera GT in front of news cameras in 2006. Wright promises a production version of the X1, but it will be heavily modified in order to meet on-road safety standards.

What did we miss? What other green scream machines would you put on the list?