I'd think you should be able to beat my beater for mileage, maybe my hills are to much of an advantage.... 2km engine off coasts....
and many many engine on coasts.
See what your auto does from neutral to Drive at 90km/h. I rev match and if I do it right, no lurching, even just going to drive at an idle doesn't produce any terrible clunking. I keep on meaning to stop at the local tranny repair place and see what they say about it. They would know exactly what's happening in there.
Keep at it, don't let my crappy neon beat you!
Ian