Very first sentence of your source says "Google’s self-driving car gathers 750 megabytes of sensor data per SECOND!", here goes one fourth of the alleged 1GB.

Very first sentence of your source says "Google’s self-driving car gathers 750 megabytes of sensor data per SECOND!", here goes one fourth of the alleged 1GB. Then this is about sensor data or raw data, but there is thing known as compression which is quite common and can shrink size by an order of magnitude. 75MB/s seems closer to reality and manageable.