The GO740 has ecoroutes too. I haven't found any difference between ecouroute and fastest either. Maybe there isn't enough data in us maps yet.
I've always questioned how this feature would operate since the vehicle itself can make such a difference. One of my vehicles has a
very low CD, and one of my vehicles is like driving a brick in the wind. The former tolerates higher speeds without nearly as much of a penalty in mileage compared to the latter. As a result, the recommendation of "eco" routing should, by rights, be different based upon which of the vehicles I'm driving. One vehicle may tolerate highway speeds better than another, changing the decision about whether or not to use or avoid higher speed roads vs secondary roads (as determined by average speed data embedded in maps). The TomTom unit knows nothing of vehicle characteristics.
Another thing that TomTom doesn't know... what's actually causing the average speed info for road segments that is embedded in the maps (IQRoutes data). Stop/start cycle driving can
REALLY put a serious dent in mileage for most vehicles. While TomTom's maps may know the average speed for a piece of road at a given time of day, they do NOT know what's causing those speeds to be what they are. Is it a slower speed limit, normally slower traffic flow,
or a long series of mileage killing traffic lights? Even the hypermilers who do their best to plan ahead for lights can't beat them when they're not synchronized (and often not even if they are). So if routing includes city driving, I can't imagine how TomTom has enough information to make an intelligent decision about that.
Last, there's the issue of traffic. Unless a unit has Live traffic (or even the lesser RDS traffic) available to it, it hasn't a clue about mileage and routing. I've taken trips that while some miles longer, avoided long stretches of stop and go traffic or idling in traffic for lengthy periods of time. In fact, I'd say that my best "eco route" feature on my 740 is the Live (now HD) traffic. This kind of decision making ability turns out to be the most important factor in "eco" routing on some trips, especially for commuters with longish drives. How could such a feature not require the availability of traffic data?
I guess I haven't a clue as to how this feature actually works, but it certainly seems that it would need certain input that it doesn't request or may not have available. I'm wondering if it's really useful or just a marketing gimmick?