The original Raspberry Pi Model A and Raspberry Pi Model B require full-size SD cards. The newer Raspberry Pi Model A+, Raspberry Pi Model B+, Raspberry Pi 2 Model B, Raspberry Pi Zero, and Raspberry Pi 3 Model B require micro SD cards.
They recommend at least a 8gb Class 4 card. Though the larger capacity cards are now cheap enough I recommend a at least a 16gb/32gb class 10 card. Such as the this one.
The card class determines the sustained write speed for the card; a class 4 card will be able to write at 4MB/s, whereas a class 10 should be able to attain 10 MB/s. However, it should be noted that this does not mean a class 10 card will outperform a class 4 card for general usage, because often this write speed is achieved at the cost of read speed and increased seek times.
The downside is the card slot is mounted on the backside of the Pi, making accessing the card extremely difficult if you mount the Pi behind the dash assembly. This can be fixed by using a Micro SD card slot extender.