Both the petrol and diesel versions of Audi’s V6 are high-performance units that will provide all the performance you’ll ever need. But for most people buying an A5, there’s really only one that’s the right engine for them and it has nothing to do with reliability.
The turbo-diesel V6 is only really happy if you’re regularly using it for longer journeys where the engine gets hot enough to regenerate its soot-filter. This isn’t an Audi-specific thing; it applies across the board to all modern, common-rail diesel engines with soot-filters. For most urban-dwelling Australians, the pattern of vehicle usage doesn’t include those critical long journeys at freeway speeds, and driving around the suburbs for 12 months without a regular gallop on the open road will almost guarantee problems with the diesel’s emissions control systems (including the soot-filter).
Which means that for the vast majority of A5 buyers, the petrol V6 is the only way to go. While you will be losing a little fuel economy over the diesel, the petrol V6 is actually a nicer engine to use and live with. It’s faster, smoother and definitely more refined. And you won’t smell like a semi-trailer every time you fill up.