I dont think there is a an exact rpm number but I was shifting around 2500-3500.
Thought I would share the experience of me getting my G since it was actually pretty funny. This was when I used to live in Sauga and I booked my test in Burlington so I didnt have to wait as long to take it.
First Test - My test was at like 430 or something and I was late leaving work. Plus travelling from sauga to Burlington at that time is suicide because of the traffic. So I was utilizing all on ramp and off ramp lanes, RIPPING it there to be there on time. I arrived at 425 and they told me that they cant do the test because of expection time and I will have to rebook.
Because it ws burlington I was able to re-book 5 days later.
Second Test - I got there on time but the examiner got into my car and said we couldnt do the test because I had a chip in my windsheild.
Few days later…
Third Test - I had to take my moms sunflower, but again I was running late going though the same traffic as before again utilizing the on and off ramps. I get off the highway to notice I was VERY low on gas, but had no time to get gas cause I would be late. So I pulled in, examier got in the car and off we went. I mentioned “I was running late and I didnt have time to get gas, I can put 5 buck in at the next station” looked at the dial “well be fine” he says. Sure enough 5 minutes in the test the car starts puttering and dies on the side of the road LOL. He jumps out of the car and starts walking back to the office. My step mom arrived 10 min later with a jerry can of gas and a chocolate bar 
Fourth Time - Got there on time with the right car and tore up the scene. Told me to look in my mirrors a bit more. NOTHING ELSE.
Sorry for the novel, people usually crack up when I tell this story.