Fitting instrumentation to an older vehicle
 

Hello all. I'm a bit new around this particular forum, so pardon me if I've posted in the wrong area.

I'm about to pick up a 1994 Saturn SC1 with the LK0 engine (85 HP) and a manual transmission. The car runs decently well, especially considering it has 242k miles on it. I already know it needs some maintenance and some repairs (I have to drop in a new radiator, but it comes with one; have to fix a problem with it idling at high RPMs; a seeping oil leak on the valve cover needs fixing; etc. etc.). I figure while I'm dinking around with it, how can I instrument it to give me better insight into its fuel economy?

Being a 1994, it uses OBD-I with the ALDL-style connector. Therefore, I'm 100% positive my existing OBD-II Bluetooth transceiver won't work here, and even if it did, I doubt Torque on my phone would be able to speak the car's language. I'm already familiar with the original method of fuel economy tracking (ye olde pad and paper, which is what I did with my old truck in college since the fuel gauge didn't work; though now I do this with an app on my phone), but I'm just trying to find how I can keep an eye on what's happening in the here and now to help me be more conscious about my driving habits.

I'm open to making some modifications to the car in the future to further improve its fuel economy, but my primary concern right now is that with 242k miles on it, and the rough Minnesota winter bearing down on us sometime soon, I want to make sure it's running (and well) and survives the winter before I start investing a lot of time and money into it. However, because it is so old I am open to making modifications to it since I know I don't really have to worry too much about resale value or making it look good. However, I'm also picking this car up because A) It's cheap to operate (people regularly report 37-40+ MPG in the highways in this car) B) A friend is selling it to me for dirt cheap — So I'm not looking to invest too much money in it, or make modifications I couldn't remove (or rebuild) and reuse in a newer vehicle further down the road.