Private vehicles: technology, legislation, and incentives

The energy consumption of individual cars can be reduced. The wide
range of energy efficiencies of cars for sale proves this. In a single show-
room in 2006 you could buy a Honda Civic 1.4 that uses roughly 44 kWh
per 100 km
, or a Honda NSX 3.2 that uses 116 kWh per 100 km (figure 20.9).
The fact that people merrily buy from this wide range is also proof that
we need extra incentives and legislation to encourage the blithe consumer
to choose more energy-efficient cars. There are various ways to help con-
sumers prefer the Honda Civic over the Honda NSX 3.2 gas-guzzler: raising
the price of fuel; cranking up the showroom tax (the tax on new cars)
in proportion to the predicted lifetime consumption of the vehicle; cranking
up the road-tax on gas guzzlers; parking privileges for economical cars
(figure 20.10); or fuel rationing. All such measures are unpopular with at
least some voters. Perhaps a better legislative tactic would be to enforce rea-
sonable energy-efficiency, rather than continuing to allow unconstrained
choice; for example, we could simply ban, from a certain date, the sale of
any car whose energy consumption is more than 80 kWh per 100 km; and
then, over time, reduce this ceiling to 60 kWh per 100 km, then 40 kWh
per 100 km, and beyond. Alternatively, to give the consumer more choice,
regulations could force car manufacturers to reduce the average energy
consumption of all the cars they sell. Additional legislation limiting the
weight and frontal area of vehicles would simultaneously reduce fuel con-
sumption and improve safety for other road-users (figure 20.11). People
today choose their cars to make fashion statements. With strong efficiency
legislation, there could still be a wide choice of fashions; they’d all just
happen to be energy-efficient. You could choose any colour, as long as it
was green.

Figure 20.9. Carbon pollution, in grams CO2 per km, of a selection of cars for sale in the UK. The horizontal axis shows the emission rate, and the height of the blue histogram indicates the number of models on sale with those emissions in 2006. Source: The second horizontal scale indicates approximate energy consumptions, assuming that 240 g CO2 is associated with 1 kWh of chemical energy.
Figure 20.10. Special parking privileges for electric cars in Ann Arbor, Michigan.
Figure 20.11. Monstercars are just tall enough to completely obscure the view and the visibility of pedestrians.