95 will make it worse. The engine management adjusts to suit the octane lvl of the fuel so the higher the octane the better it will be.
Alot of stops and starts really pushes up the fuel usage in these. Also don't fully trust the accuracy of the fuel readout. Maybe you should do a test by filling the car right up with fuel then take the odometer reading then drive around for a while ,refill and work out the useage.
Perhaps check your airfilter element to make make sure it is clean or even replace it to make sure. Also make sure your tyre pressures are up as high as they can be as is recommended.
71 429SCJ Mustang