Prius facts
Coal: The vast majority of Prius cars are not of the plug-in variety and all their electricity ultimately comes from whatever is in the fuel tank. Coal has sweet FA to do with it.
"However, the Prius does have huge batteries+a gas tank+2 engines instead of one, which makes it 50% heavier than an equivalent gas-powered car. Guess what it does to you power consumption in the traffic..."
Actually, the Prius has one petrol engine and two electric motors/generators - but one of these replaces the starter and alternator.
The Prius is a compact car (in US parlance) and weighs in at around 1300KG, slightly more than the 1.6 Toyota Auris but less than the 2.0 model. The battery pack weighs 53Kg.
Consumption in traffic is where the Prius scores highest, mainly because it can keep the petrol engine off for most of the time.
It has to be a good idea to investigate alternative fuels like algae, if only to have alternatives when the oil runs out.