I don't think that there's any measure that you could use to objectively claim that there is a 'war on the motorist' - except to count the newspaper headlines containing the phrase, or indeed politicians using the phrase to get admiration from 'hard working families' by declaring that they feel the pain of the motorist.
Take this example, from The Mirror "Labour yesterday vowed to stop demonising motorists and start championing them as it declared its war on drivers was over."
http://www.mirror.co.uk/news/uk-news/labour-car-war-over--new-4730050
In regard to costs and taxes raised from the road network it really depends on how you measure it and who you ask. However I don't think cost benefit analysis' of this nature are very helpful. You can't really put a value on quality of life. You can associate a cost to a life lost through an road traffic accident, a cost of obesity through lack of exercise, costs of traffic jams, the rational is that when you know the cost of something there's a justification to address those costs by investing to resolve the
immediate problem
Once you start doing cost benefit analysis you are already committed to a certain point of view. That is one of economic efficiency (ie it's worth making this junction safer at x cost as y amount of people have died at it. Or you can justify an extra lane on a road by pricing the opportunity cost of people sitting in a traffic jam).
What missing about such economic analysis is any kind of vision of what kind of society we want to build. Do we want to continue to invest in, and propagate a car dependant society, is the supposed freedom to be able to drive with minimal personal cost worth having at the expense of stopping children going outside at break times as the playground is too polluted, should our streets automatically be planned to allow maximum flow of cars at the expense of anyone else who's not sitting in a car.
My understanding in that planners plan for more cars being driven more often. The nihilist neo-liberal mind sent directs public money to accommodate the demand. They don't plan for less polluted streets, nor do they plan for cycling, walking, or even public transport displacing the demands of the motorist. They plan for more cars, and we get more cars.
