I would have to do a side by side comparison that features the areas that are important to me e.g.
- CO2 per mile (EIther from burning fueld and/or generating electrictiy to charge the vehicle)
- Resources used to put the car together (Environmental responsibility?)
- Total cost of ownership for the car (Insurance, maintenance, tax etc.)
- Fuel running costs (Both gas and electric)
- Convenience factors (Speed, total range, MPG, accessibility of charging points)
- Who manufactured the car and their corporate responsibility
Once you've got an idea of these factors, you can make a side by side comparison and a more informed choice.