te72;1709817 said:
I'm all for getting better mileage as technology allows, but I'd be surprised if average mileage these days is significantly better than it was in the late 80's. You'd think 20+ years would afford quite a bit better efficiency given that your average v6 these days puts out as much power as your average 80's Vette.
The problem is, as engine efficiency went up, so did safety standards, and as a result... curb weight. The CRX HF got ~50mpg, but it only had to pull around 1,713 (!) pounds. Even a tiny Mazda 2, Yaris hatchback, or Prius has to pull around 600 pounds more (actually, 1,200 more in the case of the Prius). Crash an 84' CRX HF head on into a Mazda 2 though, and you'll find out just how much safety that 600 pounds can provide (and how much plastic the CRX has in the front end, lol).
I'm chasing better fuel economy with my car, sort of. More as a curiosity than anything. I didn't buy the car for fuel economy... but I would like to be able to take it on a few long trips instead of always defaulting to our 34MPG (70mph highway) Mazdaspeed3.
When I first put my car on the road in March this year I was only getting 10mpg. Yeah, wtf indeed. I found sticking rear brake pads, dirty leaking fuel injectors (I saved the dirt from them, since it was JDM dirt), and cracked ignition coils. I painted the coils with clear nail polish (it worked!.. no misfires anymore) and cleaned the rust off the rear pad sliders. I got 2JZ side feed 440's, had them cleaned and tested (professionally), and just put them in yesterday, so I have to see what my MPG is up to now.
I have a few other plans... stuff I found from other projects I saw (motoiq project sipster) and from some of those hypermiling forums. I'm planning on blocking off the foglight holes and ducting air to my oil cooler from the main opening to reduce turbulence through the front end. My stock undertray is gone, and so is my front lip, so I'm making a complete front splitter and undertray out of either thin plywood or ABS (it will only go as far back as the front cross member). It will look better than the image that just flashed into your mind. Well, I hope. The back of the car will also be getting a few pieces of strategically placed flat ABS plastic to smooth airflow under the car around the transmission, rear subframe, and fuel tank. I'm also considering taking the stock spoiler off, it adds drag (+.02 to the cD according to Toyota) and I'm not sure that it does anything noticeable for downforce or stability. I already shaved the antenna and rear wiper (they were also both broken and weighed something). I already took quite a bit of weight out of the car too. I'm figuring the W58 is helping my city mileage, with it's taller ratio's in 1st through 3rd. My car has the 3.91 LSD, so they are even taller than they are in a non-turbo with it's 4.30 rear. Downside to the W58 ratios is the shorter 5th gear (0.85 IIRC) which hurts highway mileage. The alloy plate W58 itself is 35 pounds lighter than the R154, plus the clutch and flywheel are lighter (5 pounds less rotating mass there alone), and the driveshaft is smaller diameter and lighter by 6 pounds (than the A340E shaft I took out). The 190wt SevereGear in the trans is probably killing a MPG or two, but I'm too nervous that it's the only thing holding it together to put normal 80W-90 in there.
Anyway... pretty much anything I'm planning to do for economy is helping performance too, so it's win-win.
Oh, and also, I'm willing to bet that driving with the headlights up kills at least 1 MPG. I can feel the car slow down when I open the damn things.