Take a second look at General Motors. My first car, a 1977 Cadillac DeVille 425ci (7 liters!) had a computer that gave most of that information, including instant and average mileage, and range. That car was lemon yellow with plaid cloth seats! On later Cadillacs I owned, the computer trouble codes (I never had any except for 1 oxygen
sensor) could be checked by putting a paper clip into the data port, turning the key "on", and counting the flashes of the "check engine" light
. I carry a simple $120 tool to read trouble codes out of '96 and up vehicles.
My sorry Dodge at least displays the temperature and the compass direction.
My mother's much-newer Honda Odyssey doesn't have a compass, and she had to add a poor retrofit XM unit to get satellite radio. Even though the radio says on the face, "XM Ready", it would cost $700 to actually receive it through the original radio. There is also no trip computer.
My father's Pontiac Aztek shows in a neat scrollable display: temperature, direction, instant mileage, average mileage, tire pressure, average speed, oil life indexed to engine RPM, etc.
The car has satellite radio intuitably controllable from buttons on the wheel, and you can make a hands-free satellite phone call dialed by voice. The car emails the owner monthly with a check of essential measures, and tells you if something needs attention. If something is out of order (tire pressure uneven, service overdue, trouble code reported) the car will send you an extra email. If you crash, the car calls emergency services automatically. The emails from the car actually include details like miles-traveled-per-day, helping you with the gas budget!
I bought that first Cadillac at age 17 in 1987 and have owned many more. I don't think I would invest in an OBD II device to improve the old Dodge; I will save the money and put it into a GM truck that has all that built in to begin with! I started driving with mileage monitors and I think instant and average MPG displays should be required on all vehicles.