Over the past
six months, there has been growing levels of attention placed on diesel cars,
due in part to the social narrative surrounding air quality levels and the
increasing awareness concerning the real world emissions of local pollutants
from diesel car operation. Research conducted by a variety of different
organisations has demonstrated that a gap is present between the level of
emissions measured by the official tests (such as the New European Driving
Cycle) and those observed on the road for diesel cars (the International Council on Clean Transportation is a good source of information). This
situation has generated calls for action from the government, which is viewed
as being partly responsible for the widespread use of diesel cars due to a
circulation tax policy which seemingly favoured the registration of diesel
cars.
The figure
above displays the proportion of new car registrations in Great Britain by fuel
type between 2001 and 2015 (source: Department for Transport – Vehicle Statistics). There has been a convergence during this time period, going from an
80-20 split between petrol and diesel to a parity in registrations, which has
persisted for the past five years. However, as air quality is a local problem,
looking at national statistics only provides a partial understanding of the
situation. We’re now capable of understanding the structure of local car fleets
that are registered across the local authorities of Great Britain, which
provides intelligence regarding where diesel cars have integrated to a higher
or lower degree.
The map
above reports the proportion of local authority car fleets that are diesel
fuelled as of 2016. A large range is
apparent in this statistics, with Eden in Cumbria representing the local
authority with the highest level of diesel registrations at 51.22% whereas the
London borough of Sutton is the local authority with the lowest level at 24.27%.
The proportion of diesel fuelled vehicles also appears to be strongly linked to
the level of rurality, with areas of the England & Wales that are more sparsely populated
tending to have high rates of diesel ownership. Interestingly, urban areas that
have prominent air quality problems (such as Greater London) seem also to have
amongst the lowest rates of diesel car ownership. This could have important
implications for how to target a diesel car scrappage scheme, which is
currently been discussed as a means through which to encourage the replacement
of older diesel cars. For instance, restricting access to the scheme to those
owners that reside in Air Quality Management Areas (i.e. where there’s an air
quality problem) could prove ineffective if the problem is being generated
primarily by individuals driving in highly polluting cars from further afield.
