While this will be a little bit difficult without officially official specs, there are things we can learn and do know.
For one both Vans have an uphill battle against the class leading Transit Connect, the PM city already have several years of slogging against the TC as the FIAT Doblo in Europe.
Engines:
City Express: 2.0L DOHC I4
Promaster City: 2.0L Petrol or 2.0 Diesel
Power/Torque:
City Express: 131 @ 5200 rpm/139 @ 4800 rpm
Promaster City: ???
Fuel Economy (MPG):
City Express: 24 city/25 highway/24 combined
Promaster City: ???
Max Payload/GVWR:
City Express: 1500 lbs/4751 lbs
Promaster City: 1609 lbs/4233 lbs
Cargo Volume:
City Express: 122.7 cubic feet
Promaster City: up to 176 cubic feet
Again a difficult comparison considering the specs have still not been released yet. Most curious will be the engine choices. I mean its likely we even see the PM City sharing engines with the Jeep Renegade/Cherokee. We could end up seeing it show up with a 1.4L Turbo or even the 2.4L MultiAir.