In real-life, the M4 motorway also passes several major settlements in England (most notably, Bristol, Swindon and Reading), while both games featuring the motorway featuring virtually nothing along the road. The lack of cities in-game is reflected by the name of Cardiff appearing on road signs just outside London, Birmingham and Southampton.
The M4 in-game is broken in the middle by the M5 motorway. In real-life the two motorways simply meet each other in a large interchange. ProMods re-scripted the area such that a full cloverleaf occupies the place.
All three gas stations along the in-game motorway are of the smallest type.