Finally did it - my previous best was 36mpg, and now 41.52 mpg was returned on my 92.6 mile hwy FE loop.
My goal was to break 40mpg so now I'm not afraid to make my one-tank trip from so cal to provo utah this summer.
Since I have not installed my mpguino yet, my method of measuring FE to date is fill up with gas until its sitting above the flap valve in the tank's neck.
I do this both before and after my 92.6 mile drive on the local freeways (15 north - 215north - 91 west - 15 south).
My route is the same every time, with the same gas pump and gas station utilized both before and after.
This last fill was 2.233 gallons, a new record!
1992 Mustang 2.3/AT convertible
Current mods to the car:
144cc Denso fuel injectors
NGK G power spark plugs
underdriven crank, water pump, and alternator pulleys
3" mandrel bent aluminum intake tube
Gutted lower air box with an accel drop in filter
45psi in 195-75-14 generic radial tires
upgraded exhaust (2.25" hi flow cat, 2.25" pipe to oem 5.0 mustang muffler, to oem 2" tailpipe)
gutted trunk
Driving style during test:
top lowered with tunes blazing
1/4 to 1/2 throttle during acceleration
50-55mph highway speeds on cruise control (54mph mostly - 2050rpm)
shift to neutral on downhill coasts
shift to neutral on deceleration
shift to neutral at traffic signals
NO pulse and glide, engine off coasting or engine off decel
I'm so stoked - can't wait to add the mpguino and air dam I have bought already.