There is a road test of the Mk2 1.1 Popular (same mechanicals as the one in your pic but more square body) here :
Ford Escort 1100 Popular Mk2 & Toyota 1000 Twin Road Test 1975 (1) | Flickr - Photo Sharing!
And a test featuring a Mk1 1.3 Estate (aka Wagon) against 2 other cars here.
Citroen Ami Super - Ford Escort 1300 Estate & Renault 6 TL Group Road Test 1974 (1) | Flickr - Photo Sharing!
They don't seem to give much away but in the test it claims 28 MPG (imp.) for the 1.3 and about 29 for the 1.1. Fords of this era had auto-chokes which were notoriously unreliable which would affect MPG and engine life.
Ford went on to make these RWD live axle ancient things well after the VW Golf, Renault 5 and FIAT 127/128 had come along.
There are loads of other tests there too.