Hi all - glad I finally found some people that are as crazy about boosting gas milage as I am.
I started back in the early 70's with my 65 Rambler American flat head 6 with a little head work polishing and a new SU (constant velocity variable venturi) carburator. I also was pretty cutting edge putting radials and bias ply on an old car. I have since owned and buried a 80 VW Rabbit that got 27mpg winter and summer until I tuned it up to about 38mpg. Currently have a 1994 Geo Metro with 90608.7 miles sitting in a yard waiting for some welding work to repair the rotted out front chassis where the right A Arm connects. Last tank of gas on it yielded 54mpg over the summer several months although my record was around 60mpg on a trip out west fully loaded drafting tractor trailer trucks on the highway in western PA.
I had to get new transportation after the Thankgiving morning front wheel split - so the following Monday I had a friend give me a ride to a Scion dealer and I picked up a 2006xB the same afternoon that I am now working on a little. I have started on a rear under pan to smooth out some air flow in back and some gas additives. The coolest think is the ScanGuage which took all of about 20 minutes to decide and then order once I saw it on line. I still need to calibrate it to the gas used and the GPS indicated about 3% correction was needed to the speedo - pretty wild looking at three speedos while driving. So far I have seen the gas mileage as measured by the fillup vary between 31 and 36.8mpg and I am shooting to break the 40mpg barrier.
Yeah the rear pan is a little tricky because they put a gas fume pump and canister filter under there where the bigger trunk should have been so some stuff is in the way and needs to be easily accessable by the dealer should inspection or repair be needed. So far I started with a sheet of foamcore board (paper covered foam) that is light ridged and easy to cut to shape - left ample room for the muffler for cooling etc but found that the left wheel well could end up throwing a lot of junk above the sheet. Figure a coating of glass and epoxy to really make it strong and waterproof should do the trick then just a matter of fastening it. The rear lower trim kit that comes on the xB just sticks out from the bumper several inches and looks great until you look under the car and realize that it is a big air scoop. Blending it smooth going forward will no doubt help the air flow back there. The rear wheel skirts you have make me think a little about the xB rear and a spoiler that they claim helps ?? Maybe you could use clear plexiglass so it would not be noticed as much for testing then opt for a solid color. One thing I like about my old 5 door hatchback Geo is the reverse taper the entire body has more noticable when viewed from above the rear 1 story up. Along the lines of air drag in the wheel area I wonder how close you can make the fenders get to the wheel and then maybe use a smoother hubcap - I have the vented moons on my old Geo which I figured probably helps a little. Another thought I have for the xB is to tape off the holes in the steel wheels to keep the brake dust and road sand and grit from blowing through the wheels. They come with side moldings and some wheel skirts but definately need some more rear wheel underbody work.
It plays regular music cd's and can also read a CDRW with MP3 files and plays them perfectly and also displays the MP3 title and other info imbedded in the MP3 file. HA HA you mean Cooeficent of Drag I know - yeah it looks like a box but the leading edge is rounded A LOT and deflects the air to the sides and the upper grill is not open. The windshield is interesting with a coating of Rain-X on it the air flow pattern is surprising almost nothing in the center then it blows sideways on either side of center. Windows are not as smooth as my old 94 Geo however but the corners are beautifully rounded and the paint job is flawless. Frontal area is the biggest drawback but they lowered it to 6.1 inches off the ground and it gets gas mileage that I was very impressed with considering the size and the 2400lb unloaded weight. The big indicator was coming down the Newport Bridge coasting - terminal speed starting at 40mph at the top was 45mph vs the Geo that reached 55mph. It does however continue to roll like crazy at lower speeds and the wheel bearings have such low stiction that if you park on level ground and lean a little on it, it will start to roll. Running a bit high on the tire pressure helps a bit also - 38.4psi - I only ran the Geo up to 35psi recently usually 34psi.
Very cool, sounds like you know what you're doing, make a seperate post about the rear diffuser if you're looking for some better input. I'm working on my front undertray now with metro's advise that it did 10% of good on autospeed.com's prius.
Yeah but if I talk about it to any more groups I will not have any time left to build it. Basically the problem with EV and EV Conversion is that the vehicles are too big to begin with. The amount of power needed no matter what the form, is big, and the cost of power is forever going to increase. So I started with a basic little electric scooter frame that was made of steel and way too heavy for its own good and installed a rather expensive, high efficiency motor with beyond the legal limit power and three of the best batteries made from Lead and produced a very efficent little rocket that I can barely pick up and fits nicely sideways in the back of my Geo. Next step is to build a big Li-Ion battery pack and an enclosed cabin composite frame integrated body with room for one to sit in and figure out how to make it legal enough to drive on the roads. I may have to have working pedals. Presently I get about 20 miles per kwh of grid power used. If it were a car sized conversion it would be more like 1 to 5 miles per kwh used.