It's certainly getting on a bit now but its no bad car. It doesn't compare well to the current E Class and 5 Series but then as you've discovered neither is it priced like either of those cars now.
An A6 2.0 TDI S-Line Ultra DSG is a few hundred pounds cheaper than a BMW 520d M Sport Auto but after expected discounts for both are taken into account, the Audi is almost £5000 cheaper, which isn't to be sniffed at.
Just be careful that this discount doesn't also flow through into the expected residual, which would end up making it no cheaper to own than its more modern counterparts.
An A6 2.0 TDI S-Line Ultra DSG is a few hundred pounds cheaper than a BMW 520d M Sport Auto but after expected discounts for both are taken into account, the Audi is almost £5000 cheaper, which isn't to be sniffed at.
Just be careful that this discount doesn't also flow through into the expected residual, which would end up making it no cheaper to own than its more modern counterparts.