As far as gas prices, your driving style plays a huge role in vehicle efficiency. Investing in a PHEV or hybrid is the most inflation-proof approach to rising gas prices. You can recover a large percentage of the energy lost in stop and go traffic via regenerative braking, oil changes and brake service costs are much lower than with a legacy ICE (internal combustion engine) car.
Even if you don't have an interest in breaking away from ICE propulsion, there are other ways to maximize efficiency. Skilled drivers know that over inflating their tires by as little as 1-3 PSI over the "recommended" pressure can radically lower rolling resistance and increase miles per gallon by as much as 20%. The downside is that the ride becomes somewhat rougher, but re-training your brain to drive gentler can mitigate the impact of such. A "trick of the trade" that was told to me from a retired medallion driver on the way to the airport on early morning:
When you have a passenger onboard you should always drive 20-30% slower than you would normally, including taking turns, lane changes accelerating and decelerating." He referred to this as "damp driving" and also suggested never to go more than three of four miles over the speed limit. Not only will passengers who feel like they "floated" to their destination are more likely to tip, you will save on gas over time.
Climate control has an large impact on vehicle efficiency as well but most newer vehicles have intelligent "ECO mode" interior control that helps reduce the time your AC compressor is engaged against the drivetrain, increasing efficiency. Try playing around and getting familiar with your vehicle's climate control intimately. You'd be surprised at how much of an efficiency boost you can squeeze out.
If you want to get all techy-advanced up in here, you can invest in an OBD-II reader with bluetooth that plugs into the car's dataport. Using any number of apps you can maximize your driving efficiency like a boss.
http://www.techetron.com/11561/5-apps-help-improve-driving-efficiency/h
There are many more suggestions but you get the idea. You can turn your "20 mpg" vehicle into a 23 mpg vehicle simply by changing your driving habits and the above suggestions. While +3mpg does not sound like much, over time that extra distance translates to the economic equivalent of getting a free gallon of gas per tankful. Over a weeks time, that may translate to the equivalent of getting half a tank of free gasoline.
