This OBDII Can Bus Adapter connects to your USB port. It is a fast and very reliable way to connect to your Car.

Where to Buy

As of 2017-06 the device is available via amazon for some EUR 50

Usage on Mac OS X

After connecting the USB cable to your MAC you can check whether the device is visible. If you have macports/lsusb installed with the command

lsusb
Bus 004 Device 001: ID 0403:6015 Future Technology Devices International, Ltd Bridge(I2C/SPI/UART/FIFO)

otherwise

ioreg -p IOUSB -l -w 0

"idProduct" = 24597
...
"USB Product Name" = "OBDLink SX"
...
"USB Vendor Name" = "ScanTool.net LLC"
"idVendor" = 1027