Its lots of scaremongering going around about those issue of diesel cars,If its sort of modern vehicle then you should be okay with congestion laws as long its euro 5 or euro 6 engines things should be okay and its a low co2 emissions, all new diesels cars from 2017 onwards should comply with the tighter emissions laws with having euro 6 engines and adblu additives as that will help clean the emissions out from the car. I don't believe in getting a electric car because not economical due to short range of miles you getting from them to plus where you charge it to .Keep your current car until such time its costing you money in huge repair bills and see how the market is and how things will be with those congestion laws etc.From 2035 apparently but their will be a certain time after that date to allow everyone to change over to hopefully better electric car or a better alternative green car, then gaunantee the government will up the road tax of zero to whatever they feel like as another way to tax those of electric car's etc just like they did when they eventually realised everyone was buying cars with cheap road tax and now they up it upto a minimum of £150 plus rises to. No win situation for the government.