You can trade with the AI without there being any actual transaction in goods/gpt but still be able to gain a bright green 'We've traded recently' modifier.
I've made a video just for clarity's sake: http://www.youtube.com/watch?v=S-rCJ--IW9M
It is very easy to reproduce as this works in any stage of the game and with any save. All you need as a requirement is to have made one real trade.
So:
Additionally, it doesn't matter if your first trade only produces a dull green modifier instead of a bright green one since you can repeat the steps multiple times to have the diplo bonus stack up enough for it to become bright green. This means all you need to give away to get a few good relation points is 1gpt.
I've made a video just for clarity's sake: http://www.youtube.com/watch?v=S-rCJ--IW9M
It is very easy to reproduce as this works in any stage of the game and with any save. All you need as a requirement is to have made one real trade.
So:
- Make a favourable deal to an AI that gets a 'We've traded recently' modifier.
- Now go back and select the 'Declare War' option but cancel it.
- Go back into the trade screen and your last deal you've made with any AI will show up.
- Accept the deal to get the bonus (no actual transaction happens).
- Now you can go around to all AIs and offer them the same favourable deal to get easy diplo points.
Additionally, it doesn't matter if your first trade only produces a dull green modifier instead of a bright green one since you can repeat the steps multiple times to have the diplo bonus stack up enough for it to become bright green. This means all you need to give away to get a few good relation points is 1gpt.