Well, all I can offer is my own experience with that A8; a 2011 car bought almost new. Did c. 100k in it, never let me down or indeed even broke. 45mpg easy, 50+ achievable, I drove from Saffron Walden to Montpellier on one tank... about 800 miles.

£300 for a service every 20k miles, I had 18" rims with winters on it from Oct to March then back to 20's for the summers.

Anyways, best of luck. if your heart is set on the fattie then go for it! Graham

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Gone: 10MY L320 RR Sport HSE, Ipanema Sand
Gone: 20MY Jaguar iPace HSE, Silicon Silver
Gone: 17MY RR Evoque SE Tech, Loire Blue
Gone: 08MY Discovery 3 XS, Stornoway Grey
Gone: 07MY FFRR TDV8 Vogue, Stornoway Grey

another vote here for the a8 if you dont have dogs-3.0 tdi...lovely cars esp the 2010 onwards model