The tune is certainly the critical factor! The best I've ever had in the past was about 500k to a tank but that was manual car and XR6 cam - more typically with the JMM cam and Auto I'd been getting around 400 to maybe 450 - but in recent times I've finally been getting close to a sorted Tune on TI Performance J3 (programming it myself) and have been pulling figures of just over 600k mixed highway / town - on normal ulp.

The tune I'm ending up with looks fairly drastically different to any others I've ever seen and is awful rough inasmuch as I'm not even using an AFR meter (going to get one soon tho) - but just picking up when she's happy / not happy and at what revs and throttle and trial/erroring from there.

Running lots of timing but also pretty high VE values - ie. the tune to the eye looks WAY rich - but it's simply what the engine wants - she goes ball busters and the result is awesome economy as well as great power. It actually blows black smoke off the line - but that's what it takes to kill off idle hesitation and the smoke notwithstanding she hauls a***. The good mileage is because the engine is really doing everying easily - god knows what it might return if I actually try driving it carefully!! And we're talking 30+ degrees North and central Qld...

We've just moved and don't have internet going just yet (usin work pc right now) - but once I have home internet again I'll make my tune available. It's likely to be a bit specific to my car tho - running a big JMM cam at least several degrees late. The late timing mite also explain the odd look of the final tune... Whatever... - it all works

In my wifes AU-6cyl Auto 4sp I get 750-80 klm it is the most economical we've ever owned & it has done it three times on trips from Penrith to Foster (always over 700 best was 785 & still had 12 DTE) drove for a week up at Forster then back home... I was so careful driving with every known economical trick I know, always in cruise control on freeway, windows shut, no roof racks etc. tyres air perfect we even used Air\Con some of the time... Never gunned it through the gears & I tried long coasting to L+R turns rather than brake at last minute ...