For some time automakers have been under increasing pressure from the government to make their cars as green as fuel efficient as possible in order to improve air quality, reduce pollution and diminish our dependence on fossil fuels. 

But makers of  medium and heavy duty vehicles -- like semis, buses and 3/4 ton pickup trucks  -- haven’t been put under such pressure to improve their vehicle’s fuel efficiency. 

Until recently, that is. 

Earlier this month, the government released the first ever fuel efficiency standards for medium and heavy-duty trucks, requiring improvements in fuel economy which could save as much as $50 billion in fuel costs by 2018. 

We first heard about the EPA proposals back in October last year -- but what does it really mean for those of us who drive regular cars and not huge trucks? 

Better than a fleet of Prii

Big-rigs -- or semi-trucks -- will be required to improve their fuel economy by 20 percent by 2018, saving up to 4 gallons of fuel for every 100 miles traveled. 

Why is this important? 

Improving the fuel economy of a truck which can get between 5 and 7 miles to the gallon by 20 percent has a larger effect on both emissions and operating costs than a whole fleet of Toyota Prii. 

In other words, the larger and more fuel inefficient, the larger the environmental impact is of improving its efficiency. And changing the fuel efficiency of larger, more polluting vehicles by a factor of 20 percent is much more important than actual mile-per-gallon figures. 

And because the cost of running high consumption trucks like semis, buses and garbage trucks are so high due to high fuel prices, upgrading to a more fuel-efficient truck saves more in fuel than the cost of upgrading.

 It isn’t just about the truck-drivers

The new fuel standards aren’t just about improving fuel economy figures and reducing fuel bills for truckers, transit providers and municipal departments nationwide -- they’re about economic stability.

Take a truck shipping groceries from one city to the next. At a mind-bending cost of just under $4 per gallon for Diesel, traveling just 250 miles in a 7-mpg truck could cost as much as $143 $80 in fuel alone -- which is of course, passed onto the consumer.

Reducing fuel consumption -- and therefore fuel costs -- by 20 percent helps to keep the cost of transporting everything from vegetables to gasoline lower.

And of course, we’d hope those savings would be passed onto the consumer. 

It benefits local communities too

Just like big-rigs, more fuel efficient busses not only reduce pollution in inner cities, but also reduce the running costs for transportation authorities already struggling with the burden of tighter budgets as local governments fight to cut deficits. 

Cheaper, cleaner buses -- also mandated by the new 2018 targets -- mean transit authorities can reduce the cost of tickets, encouraging more commuters to leave their gasoline cars at home and take the bus instead.