I have heard of people using injector kill switches but they were on manuals I think.
one thing that I always like to suggest is a scangauge. it is a large initial investment but being in the EE field myself, I think you would find it fun to play around with. it does only work for 1996 and newer cars but most people fall under that category. it is $160-$170 and most of us on here have at least one.
it tells things like MPG (trip and instantaneous), rpm, mph, gpm, tps, and too much more to list.
www.scangauge.com but they are available elsewhere. sometimes you can even get lucky and find one on ebay used for around $130.
there are other mods but this was my first and usually the first that I recomend to others.
welcome to the site.