The GMO that I am finding interesting is cynobacteria that is modified to 'sweat' out sucrose. Proterro is currently conducting a prototype unit that is taking genetically modified blue green algae to produce straight sucrose. The projected cost of this is about 5 cents a pound, verses about 3 times that for corn sugar.
This can be processed into ethanol, or another company came up with a process for turning sugar into gasoline.