My car's at 112k mi, and burns 0 oil. I run it on Delvac One synthetic, and run synthetic tranny and diff fluids.
I drive the car a 60/40 split of in city/highway driving, and the car idles a fair amount. I consistently get 25-27 mpg combined, and I drive the car HARD (I also drive a 500E, so I'm used to getting from point A to Point B in short order). I'd think you're mileage is great, and would perhaps be a bit better if you were firing on all 5 cylinders. And unless your injection pump is really leaking violently, the amount of fuel lost is negligible I'd think.
So, let's get that puppy up to 300k!
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car