Now that oil is more expensive and scarcer than it has ever been, will we see a return to the lower speed limits of the '70s? It is a well-known fact that driving more slowly saves fuel and keeps emissions down. But is driving like grandma the best way to save energy?

There's a sweet spot between 40 and 60 mph that yields the highest fuel and emissions savings. Driving faster, like 75 mph, or much slower, like 25 mph, both result in increased gas and emissions. Drivers add up to thirty cents more per a gallon to the cost of their mileage for every 5 mph above 65 they drive because efficiency declines. Detractors such as the Heritage Foundation claim that limiting speeds to 55 mph only saves 1% of fuel over a decade. Yet, thinking of how much fuel 1% of US consumption actually ends up being (146 billion gallons a year times 10 years divided by 1%... you do the math) a really humongous volume of fuel.

One of the most environmental presidents ever, Richard Nixon, set the first 55 mph speed limit in tandem with Congress, and it lasted through the Carter administration. Congress leveraged highway funds for state compliance. Though unpopular then, people lived with the speed limits.

Now, the policy is struggling to find traction despite a swath of environmental and safety NGO support. Republican Maine Senator Susan Collins told reporters that reviving the 55 mph speed limit isn’t in the cards. "While some states may decide to lower the speed limit in order to conserve energy and some drivers may simply drive more slowly in order to get better mileage, I do not believe there is support for a federally mandated 55 mph speed limit.”

Whether or not Congress makes the move to lower speed limits nationally, commuters should heed Senator Collins’ words and take the initiative to drive slower if they care to save fuel.