The simple explanation of the technology is a box is connected to a vehicle emissions system and collects most of the gases and emits primarily water vapor. You change it at every fill up. Then
Through a chemical reaction, the captured gases from the box would be fed to algae, which would then be crushed to produce a bio-oil. This extract can be converted to produce a biodiesel almost identical to normal diesel.
This biodiesel can be fed back into a diesel engine, the emptied Greenbox can be affixed to the car and the cycle can begin again.
The process also yields methane gas and fertilizer, both of which can be captured separately. The algae required to capture all of Britain's auto emissions would take up around 1,000 acres.
That's quite a bit for something that connects to your car exhaust. If this thing is real and can do all it says it can this will change everything. That's an understatement but how else do you say it. I'm looking forward to more coming out on this about the science and feasibility behind it. Let's keep our fingers crossed.