This plug-in hybrid version of the A6 makes a lot of sense as a company car, thanks to its tiny official CO2 emissions. What's more, it can travel for up to 34 miles on fully electric power, and when the petrol engine is needed, it springs into life quite quickly and very smoothly to give 0-62mph in 6.2sec. The brakes are more precise than those of many plug-in hybrids, too, but you will need to plug the car in frequently to get anywhere near its official fuel economy.