You have the Duratec family of engine under your bonnet

unfortunatly, the weight of the mondeo is going to count against you tuning your car as its naturally aspirated (no turbo).

the same engine is found in the fiesta ST so parts are available even if there not listed for your vehicle.

the engines respond well to breathing modifications including aftermarket manifolds and exhaust's, new camshafts and performance replacment air filters.

a new exhaust manifold and air filter wont net you much on their own, but combined with a remap should see you to 160bhp quite easily.

you may find that the Fiesta ST has a more performance orientated set of camshafts and inlet manifold as standard and would be an easy swap into your mondeo engine.

I think 38mpg is a bit far out of reach though, the turbo diesel is a better choice of engine for a large car like yours in terms or economy and performance in my opinion..

Josh