There actually isn't a great deal of difference in BIK tax between the 190PS 2.0 TDI auto and the 252PS 2.0 TFSI auto. Currently the annual BIK tax charge for a 40% tax payer in the 2.0 TDI S Line S Tronic is £4164, while in the 2.0 TFSI S Line S Tronic it's £4570. Both will increase by a similar amount from April. Yes, fuel consumption in the diesel will be lower than for the petrol, but if you're a low-mileage driver in London, it will be poor anyway. It's true that the Mayor of London wants to impose a higher congestion charge this year for more polluting vehicles, but it applies to older petrol and diesel cars - typically those registered before 2005. However, you might also want to consider some London councils seeking to impose higher parking charges for diesel vehicles too. Despite these decisions being applied irrationally across diesel cars, regardless of whether they might be newer, cleaner models, the cost of using these areas regularly would offset the reduced fuel costs of a diesel. We would probably still choose a diesel version in 2017, but we think cities are becoming less tolerant of diesel cars, and will continue to make it less attractive to use them in built-up areas by finding new ways to impose charges.