2012 Vios 1.3 MT
I drive along EDSA everyday during rush hour
(back & forth around 14-15km only depending on the route I take, so that's roughly 7km one way) the lowest FC I got was 8km/L, with the aircon on and never did I get out of any traffic. Worst traffic I experienced was being stuck somewhere for around an hour or so, and yet, the FC was constant at 8-9km/L.
Boy I tell you malakas na yung 8km/L.

Meron nga nagpapanic na kapag bumaba ng 10km/L FC ng Vios. :lol:
When the traffic clears out, on city driving best I got was around twelve. Highway I got around 19km/L. 21km/L is achievable but I was too impatient to drive * a constant of 80kph.
Vios' ODO is 1k+ only.
Also, I've driven a 2.7L VVTi Fortuner. Traffic as well, and it was a lot longer than your 90 mins, there were a lot of stops too (w/o the engine being shut down) as I had to pick something up at various places. FC, according to the MID is 5.8km/L. Give and take 1km/L less, that's around 5km/L. Fortuner's ODO was 80k.
The FD we have here at home also experience traffic on a regular basis, if I remember correctly, the worst FC it got was around 6km/L.
FDs ODO 60-70k kms
For a 1.4L, 4km/L is simply unacceptable, for me... at least. However, if I was driving a 2.5L FXT (got around 5km/L on it last time I drove one...) or a 4.8L V8 Expedition masaya na ko sa 4km/L hehe.
FXTs ODO ~20k.