I didn't have enough time to participate actively to the Gauntlet Distance Team Challenge with the team I am in, so I decided to set up a one man team to test the new features that FEMA introduced in version 4, especially new mini-rewards, that are distributed once the team reaches certain targets in the challenge itself.  In this challenge they were in R$ and in GC, starting from 20k R$ for driving 55 miles, to 40GC for reaching around 2,400 miles, with others in between.

The most notable thing to know is that unfortunately mini-rewards achivements are recorded at single player level, not at team level.
To prove this, after I achieve the 80k R$ mini-reward, I dropped my first Team and created a new one from scratch, just to see that all the mini-prizes collected with the previous team were shown as already cashed.
I didn't have enough time to get the mini-prizes in gold coins (for a total of 60 GC), that anyway may have been achievable by a determined grinder.

I gained a total of 150k R$ in mini-prizes (20 + 50 + 80), and a final prize of 200k R$ for arriving 8660th with the second team I created, with just 312 miles.

So the total was 350k R$ for driving some like 900 miles (adding miles driven with the second team to the ones driven with the first). If I ran all the 900 miles with the same Team, I could have cashed much more, 900.000-1.500.000 R$.

I could have also tested the effects of other things like cloud saving/restoring, but (my fault) I didn't this time...

All in all, I can say that for hardcore grinders looking only for gold, running those type of challenges as a Single Man Team may be an option, at least at the rates of that specific challenge.

With 2,420.4 miles, one could have got 60 GC in mini prizes + more than 1.000.000 R$ (150k iin mini-prizes + final prize betwen 1.500.000 and 1.000.000), to be added to the fame and R$ collected just for running all the events.
Don't want to say that ~2,500 miles are simple to achive, but I have seen many people with more than 4,000 miles that cashed a lot less, because to get more than 60 GC in a standard 20 members Team one should have placed 1st or 2nd overall (2nd team got 1,200 GC = 60 for each team member, to be added to the 3 GC in mini prizes)...

Still the 10 lappers at Lemans with the 2014 LMP1s should be more GC effective, but maybe not at very high level, when it takes a lot of races to advance of one level and get the GC reward for that.

Attachments:
first mini prize (first team):

Second mini prize (first Team):

Third mini prize (first team)

After I dropped the first Team and created the new one, the mini prizes achieved with the first team were shown already cashed, even if I didn't travel a single mile with the second team.

Final prize (second team)