DIY as in real Do-It-Yourself from scratch.
I am Andrey, I am involved with
www.rusefi.com - that's a project to develop an open-source DIY engine control unit. I hope that this might be relevant - if you have full control over ECU logic and firmware you can potentially implement all kind of fuel-saving features, starting from alternator charging control to maybe shutoff @ stoplight?
Anyway, back to rusEfi. This is all still pretty alpha version, we only have two engines running this. We have our Frankenstein board we use for ECU hardware:
And we have a wiki/forum website. Oh, and as I said - we have two engines running this, another one can join maybe later this week:
So if anyone would be interested I would love to help with setting you up for rusEfi DIY ECU
Another thing -
there is a KickStarter project behind this: https://www.kickstarter.com/projects/312898525/rusefi-gpl-automotive-engine-control-unit-ecu-firm