Joking aside, driving your whole journey is becoming more attractive, as both fares and the cost of tube station parking rise. Meanwhile, if you have a parking space provided by your employer, you don't even get taxed on it as a benefit-in-kind, and unless you commute into the about-to-shrink Congestion Charge Zone, there is no road pricing. There never was a war on the motorist - the cost of motoring has gone down over the past 10 years - but there sure is a war on the public transport user, and the coming rises in fuel duty won't do anything significant to change the balance.
Maybe a few more people will look at cycling to the station instead, but with the parlous state of cycling infrastructure in the outer London boroughs, as well as the lack of secure cycle parking at stations, they may not look at it very long. For example, Morden tube station has a 120-space car park but no cycle parking.