I think this new Vehicular Emissions Scheme (VES) is out to collect more money from car buyers.
Even the Toyota Prius is not spared: it shall moved to a neutral band under the new scheme.
Just look at the measures that the Government has implemented for the past few months:
1. Increase in parking coupons;
2. Increase in PAP's Town Councils' S&CC;
3. Increase in water charges (30%);
4. New Carbon Tax;
5. Re-banding of VES.
All were given in the name of either long-time haven't increased, water is a strategic resource, more environmentally friendly.
The Government is racking its brains out, as the 2017's Budget is expected to have a basis deficit of $5.6 billion; they expect to plug this gap through the Net Investment Return (NIR) incomes from Temasek and GIC.
So, I would suggest that you spare yourselves doing all the analysis and spreadsheets on which car has the lowest carbon footprint and the lowest VES surcharge or highest rebate, the Government has already covered all the angles.
The only carbon "neutral" transport now is Bus No. 11.