From the company car perspective - I can only assume the monthly cost of the car will increase (due to faster depreciation and higher road tax). This is likely to lift some cars out of some people's company car bandings... and make the new BMWs super attractive.
Thing is though the higher tax will increase the cost of a company car by what, £20-30 a month? And the sort of person at the salary level required to justify a BMW 545i for example isn't even going to blink at that.
All it's going to do is prevent people on very low incomes running large engined cars. Which from a social point of view may or may not be a good thing depending on your opinion...