I just moved up to a 2018 A5 Coupe from a 2018 A3. In anticipating DIY oil changes I note that the A3 takes more oil (5.7L) than the A5 (5.4L) even though they have the same engine. When I look at the 2018 A6 with a 2.0L engine, it takes even less oil (5.0L) than the A5. These numbers come from Audi's spec sheet for the 2018 model year. Why would the same engine take less oil in engines that put out more HP & torque? I get that electronic tuning could account for the power (can't imagine the HP comes from a bigger turbo as that would require more oil) and that the longitudinal engines could use a different pan, but why even lower capacity in the A6 from the A5 as both are longitudinal?