I'm surprised by your oil temps as they are comparable to what I see in our 2.5; previously I had the impression the turbo worked less on hills and had a lower temp.Just got back from a long weekend trip to LA and San Diego. Basically got 27.5 to 28 mpg on both of the long drives. (Car is a Touring XT).
Coming back north from San Diego, I was sitting at a bit over 30 mpg a bit north of Valencia / Santa Clarita (30-40 minutes north of LA), just before starting the climb (on I-5) over the "Grapevine". But between the climb, and a traffic jam due to a brushfire near the highway, I never got back to 30, even after coming back down into the Central Valley. Adaptive CC was set to 76 for most of the drive, and a bit farther north there was somewhat of a headwind.
I would also say that my tires were probably a pound or two lower than ideal...
One other comment is that I had the oil temp widget on display when I went up the Grapevine, heading. It was 100 degrees at the lower elevations, and my oil temp was around 205-210 while cruising on level roads. Going up the Grapevine north-to-south, the oil temp got as high as 237 on the steepest part of the climb (which takes you to 4100 feet, roughly). Nearer the top of the Tejon Pass, it was less steep, and the temp had dropped to 225. Going northbound, it only got to around 228, and on the long downhill coast it dropped to 195. The coolant temp gauge never wavered from its normal full-operating temp, so it was interesting to watch the oil temp change a bit, with varying load on the engine.
Total distance from San Diego to home in the SF Bay Area (East Bay) was 470 miles, which was done on one tank of gas, with a bit of gas to spare. Such a pleasant car for long highway drives!
Optimum speed seems to be about 50. The best tank measured at the pump for us was 38 in our 19 2.5 during an extended stay in Yellowstone where the park speed limit is 45.