I thought the Prius was pretty poor on fuel economy?, tests in the UK place it below modern diesels. Performance wise it's considered better than most push bikes, but not the best ones!
Actually, of all cars currently on the SA market, the pruis has returned the best fuel consumption figure of all, note all cars are driven exactly the same way on exactly the same roads to perform the test, the weather can obviously not be controlled.
The prius returned 5.3l/100km and claims 123 gm/km CO2. Not bad.
But...
Keep in mind it's powered by a 1.5l engine - 57kW & 115Nm PLUS the 50kW 400Nm electric. Has a power to weight ration of 60. That tells me it's rather heavy.
Now look at this, the Citroen C1 has a 998cc 3 cyl. engine (petrol). 50kW 93 Nm.
It's slightly slower than the prius and returns 5.5l/100km with claimed 128gm/km.
If you take the technology that has gone into the prius and compare it to that of the C1 allong with the price difference between the two, I'd have to say the C1 has to get the "green" award, not the prius.
And to be honest, I'm not even a fan of french vehicles.
If you think the C1 might be a bit small, have a look at the other close rivals, Ford Ikon 1.4 tdci, biggest space and boot volume in the "green segment", very close to the above two along with the micra 1.5dCi
If that's not good enough for you, also check out the Fiest 1.6tdci, Hyundai Getz 1.5 crdi and clio 3 1.5 dci.
But whatever you do, stay away from these real small korean, indian and chinese offerings, they return horrible fuel figures and are far more polluting than much bigger engined vehicles.