The Aston's latest engine and other modifications have brought an improvement in fuel consumption, although an overall combined figure of 19.8mpg isn't likely to have the Friends of the Earth posting flowers through your letter box.
The fact that this is accompanied by of 333g/km CO2 emissions is actually not as financially prejudicial as it seems, because it costs no more to tax than a car with an output of 265g/km.
But your first year tax disc will still cost four figures and every one thereafter a substantial amount. It also shows just how much further still the DB9’s consumption must improve before even thinking about worrying a lower category, and it's a void we don’t imagine even an eight-speed gearbox with stop-start will come close to bridging.
If you’re buying new, depreciation is of the 'sharp intake of breath' variety, with cars losing around half their once considerable value in around four years. That said, you can buy a Bentley Continental GT Speed and be no better off. If you really want to cling to retained value, you’ll need to look at something like a Ferrari California to do it.
All Aston Martins are supplied with a standard three-year unlimited mileage warranty.