Diesel is seeing a huge surge in demand, and ExxonMobil says that jump will eventually lead the fuel to become the number one choice for transportation worldwide in just seven years. The move away from gasoline is being propelled by an increase in light-duty engine efficiency and an expansion in commercial transportation globally. All told, diesel represents some 70 percent of all growth in transportation fuel demand through 2040. That's according to Outlook For Energy: A View to 2040, a report by ExxonMobil.

While the company predicts gasoline demand will stay fairly flat for the next few decades, the diesel-powered heavy duty vehicle segment is expected to swell by 65 percent over the next 27 years. Meanwhile, developing nations will experience an 80 percent increase in commercial transportation.

Where, exactly, do hybrids fit into this equation? ExxonMobil projects the cars will become less expensive by 2025, which should precipitate a jump in popularity. Full hybrids will make up about 40 percent of the global vehicle fleet by 2040, though electric and plug-in hybrids will still be just five percent of the market by that time. You can take a look at the full report here.