I've always been a big fan of the new Audi A8, but it is very expensive to buy new and the depreciation is a killer. But the depreciation is an advantage if you don't mind buying secondhand like I did. Instead of buying a new Audi A6 I chose a secondhand Audi A8 in mint condition, it depreciated almost 70% in 3 years.
The build quality is stunning, everything has a perfect look and feel and the car feels like a perfect piece of engineering. And of course not a single rattle to hear in the interior.
The A8 has air suspension so the driving comfort is superb. And even though it is a big and heavy car, it's quite agile and fun to drive too. But it really shines on the motorway, you can easily drive 200km/h and feel like you are sitting in your sofa at home. Absolutely amazing!
Performance of the 4.0 V8 turbo diesel engine is fantastic. It's much more refined then the 2.5 TDI in my old A6, and a lot quicker.
Diesel consumption is 12 liter per 100km which is quite good, but still the car is expensive to maintain in general. Because this car is so advanced you are obliged to go to a dealer with it, so servicing bills are very expensive. My last service bill was over 1000€, just normal maintenance and new brake pads and discs.
If you love the A8 and you consider buying a new car for 45000€, consider spending 35000€ for a used Audi A8 and keep the rest to cover maintenance and higher running costs in general.