In the past four decades, cars have grown significantly cleaner and more fuel efficient, but it's been a bumpy road getting there. These are Jalopnik readers' picks for the ten most expensive, inefficient measures to make cars "green."

Welcome back to Answers of the Day — our daily Jalopnik feature where we take the best ten responses from the previous day's Question of the Day and shine it up to show off. It's by you and for you, the Jalopnik readers. Enjoy!

Photo Credit: GM

10.) Solar Power

Suggested By: 3pedalsgood

Why it failed: The Solar Car Challenge is a yearly competition for high schools to build and race a solar-powered car. It's a fine idea for getting people involved with engineering. But solar-powered cars? Other than a limited use of solar for powering accessories in vehicles like the Fisker Karma, it's not happening anytime soon.

Photo Credit: Pspatry

9.) Cadillac V8-6-4

Suggested By: zacarious

Why it failed: Today, more and more engines employ cylinder deactivation. What the systems do is shut down a number of cylinders when the driver is just cruising on the highway, using very little throttle.


Back in 1981, when the technology was new, GM decided that Cadillac should try it out to make their big V8s more fuel efficient. The engines were completely crude, the shut-off was the opposite of smooth, and the cars broke down regularly. Oh, and it produced 140 horsepower out of six liters of displacement.

Photo Credit: Cadillac/Old Car Brochures

8.) California's Cool Cars Initiative

Suggested By: Buckus

Why it failed: California's Air Resources Board has one of the least enviable jobs of a government agency: cleaning up the air in a smog-ridden state that loves cars. Some of their draconian rules about smog equipment and old car certification can be seen as necessary evils, but CARB's "Cool Cars" plan of the late 2000s was a complete flop.


The idea was to reduce the amount of air conditioning people would use. Air conditioning uses engine power, which sucks gas. The regulation would require manufacturers to use reflective paints in their cars. First, people thought that CARB was banning black paint, and then they realized that most of the heat soak in cars was through the windows. Over fears that GPS systems, cellphones, and ankle monitors wouldn't work, CARB gave up on the whole plan in early 2010.

Photo Credit: Hashem Akbari, Berkeley Lab

7.) Arizona alternative fuel rebate

Suggested By: iowncalculus

Why it failed: Back in 2000, Arizona offered to pay half the cost of any alternative fuel vehicle, in an effort to promote clean cars and improve the state's surprisingly bad air quality. People figured out that they could fit a one-gallon compressed natural gas tank to an SUV and get the state to pay half the price.

When Arizona realized they would be paying half the cost of $50,000 leather-lined Excursions at an estimated total cost of $600 million dollars (that was 10% of the state's yearly budget) they quit the plan, leaving people to foot the bill on these CNG-equipped vehicles themselves.

Photo Credit: GMC

6.) E85

Suggested By: Viperfan1

Why it failed: Corn ethanol seems to make sense – there's too much corn in the Midwest, so why not make it into a fuel that's got a higher octane rating than pump gas? Well, you can't put it in a pipeline, so you have to truck it everywhere, and it cuts into your gas mileage. Biofuels are really fantastic, but E85 is not the way of the future.

Photo Credit: Getty Images

5.) CAFE's light truck loophole

Suggested By: KillerKoala

Why it failed: CAFE stands for Corporate Average Fuel Economy. It defines how fuel efficient a car manufacturer's vehicles must be, and it is broken down into different categories based on size and weight. Each different kind of vehicle has a different standard.


CAFE started out in the 1970s with much lighter fuel economy standards for light trucks than full-size family cars. This seemed to make sense, as trucks were used for work, and businesses needed cheap, powerful engines. US carmakers, however, capitalized off the growing market for recreational trucks and started building SUVs intended for people to just drive around in. These SUVs were cheap to build ad they didn't have to comply with the tough emissions and fuel economy standards of regular cars.

This loophole meant that Americans just switched from driving big, heavy sedans to big heavy SUVs, without effecting any real change in fuel economy.

Photo Credit: Ford

4.) SUV hybrids

Suggested By: claiborne

Why it failed: The most egregious manifestation of the light trucks loophole are SUV hybrids. The worst offenders are the ones from GM and Chrysler that come with big "Hybrid" badges to show off their mileage numbers bested by just about any station wagon on the market. In cities where hybrids are allowed special privileges, like exemption from London's inner-city congestion charge, they're just insulting.

Photo Credit: Cadillac

3.) Cash for clunkers

Suggested By: My X-type is too a real Jaguar

Why it failed: The idea behind cash for clunkers was to get people out of smog-producing old cars and into new fuel-efficient ones. New car sales spiked only for a few months, used car prices have gone up and stayed up, and we've seen the death of all kinds of strange, beautiful old machines. It wasn't worth it.

Photo Credit: Detroit Free Press

2.) GM's EV1

Suggested By: Wolc

Why it failed: Everyone loved the EV1. Everyone but GM. The car was doomed to slow sales, so GM cut the program early and crushed the cars. Ask anyone who owned one and they loved it. While Toyota was content to lose money for years developing the Prius, GM couldn't stand a little bit of an investment in clean tech.

Photo Credit: Associated Press

1.) 55 MPH speed limit

Suggested By: Irving Washington

Why it failed: In the year following the 1973 Oil Crisis, the Congress enacted the Emergency Highway Energy Conservation Act setting a national speed limit at 55. The double nickel was supposed to greatly cut fuel consumption and the ensuing pollution, as cars create significantly more drag at highway speeds. studies found it was a mere 22-45% as effective as anyone hoped.


This hellish restriction on the nation's transportation network was finally fully repealed in 1995, after getting bumped up to 65 in December 1987. It was a dark time for this country.

Photo Credit: Associated Press