Heath, yeah I think being able to watch the voltmeter would be better than the ECU lights -- but I did forget about that feature. I think you're right -- that basically lets you see the cross-counts, but you may still be on the rich side of things.
P.S. -- Yeah, 30 mpg in the Caddy (yes, Northstar V-8). That's cruising at standard Interstate speed (65-75 mph) through the Piedmont of North Carolina and Virginia (gently rolling hills, mostly flat). The SLS and STS both are rated at 17/26, but the SLS (my car) has a 3.11 final drive vs. a 3.71 in the STS, so I KNOW the SLS can get better mileage (and does in my case). I don't know why the EPA ratings are the same for the two cars. At 80 mph, I'm turning about 2000 rpm. At 55 mph, less than 1500 (in OD). At those speeds, it's effortless (just sipping the fuel). I generally get about 20/30 city/highway. Less on the highway if we're going through West Virginia or something. Through the mountains, it's more like 26 or 27. But I run the snot out of it around town, so I'm impressed at what I get in the city. Ain't no carbon buildup in either of our vehicles.
