Any updates on your '93 project?
I've got a '91 BRG that I've been working on for better economy as well. A few things you may want to consider doing later down the road that truly help improve mpg's...
* An aftermarket front spoiler (lip) as they call them. I thought about getting the stock R Package lip, but decided on the Garage Vary lip instead as it's bigger, effectively getting the front of the car closer to the ground. I haven't measured it, but if I had to guess, I'd say the bottom of the lip is roughly 3" off the ground.
* Lowering the car about an inch to inch and a half, either with slip-on adjustable spring perches or full coilovers which I have. Measuring from the center of the hub to the wheel well, I'm sitting at 12.25" front and 12.50" rear.
* A free flowing exhaust system including NOT a 4-1 header but a 4-2-1 header as they are better for low to midrange power. A free flowing cat and muffler as well, all 2.25". I find this to be a great combo to the stock intake.
* Shave as much as weight as you see fit. So far, I've removed 135 lbs from my Miata and plan to remove a little more by deleting the power steering. I'll elaborate more on the weight shaving if there's any interest.
* I haven't done this yet, but I plan to in the near future, which is do a small cutout on the rear bumper. It traps quite a bit of air back there like a parachute, so trimming a few inches off of it will reduce this drag.
* Get a good 4-wheel alignment! I have aftermarket 15x7 (14.7 lbs) wheels with 205/50-15 performance tires with a fairly aggressive alignment and actually saw an increase in my mpg's after the alignment.
I've done all of the above except for the power steering delete and rear bumper cutout. All of this allowed me to achieve 30mpg keeping up with traffic (between 75-80mph). In complete stock form I could only manage 31mpg doing a constant 60mph, or about 25-26mpg at 75-80mph.
Now, doing 60mph and some hypermiling, I've done a best of 37.8mpg on my last tank, managing 393 miles to that tank. I'm still "feeling out" the car as far as hypermiling is concerned, figuring out optimum shift points and acceleration rates. So with every tank, I'm increasing my mileage a bit more. I'm sure I'll see over 400 miles on this tank.
BTW, I travel 112 miles every day, 100 miles on the highway at 60mph and the other 12 miles in town between 25-45mph. In town, I can actually coast nearly half of that. While on the highway, I only coast on the downsides of hills and overpasses. I have yet to do any real Pulse & Glide as I can't see how that's going to help me on the highway, not to mention there always seems to be too much traffic to attempt it.
Anyway, here's a pic of my little pride and joy!
One more thing, I too have replaced ALL of my exterior lighting with LED's, minus the headlights of course. I even converted my left backup light to a fog light with a high-output LED.
