OBIE 1.1

the author of this app says:

OBIE is an excellent and easy to use Automotive Gauge Display that lets users access real time data such as boost, coolant temp, and miles per gallon through the OBD-II port.

YOU MUST PURCHASE EXTRA HARDWARE FOR THIS APP TO WORK THE HARDWARE NEEDED IS PLX KIWI WiFi.
http://www.plxkiwi.com/kiwiwifi/hardware.html

OBIE brings important vehicle information to a user's vehicle with a intuitive design for quick access to three scrolling gauges.

OBIE supports the following parameters (also depends on vehicle itself)
Ambient Air Temperature
Barometric Pressure
Boost (MAP)
Coolant Temperature
Engine Load
Fuel Pressure
Instantaneous Miles Per Gallon
Intake Air Temperature
Oil Temperature
Speed
RPM
Timing Advance
Throttle Position
Voltage
MIL Status

Future Updates in progress

What's New in version 1.1

Fixed Menu Button bugs

Please contact support@theappleseedstore.com for technical support and bug reporting

Requirements

Requires iOS 4.3 or later.