Mother's Own Hybrid Car!

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MOTHER BUILDS HER OWN

For a good many months now, MOM's researchers have been conducting exhaustive tests—and compiling valuable data—on several different hybrid car versions . . . finally settling on a vehicle based upon a 1973 Subaru sedan for our "test unit". And despite the extremely mountainous terrain typical of our western North Carolina home (hills and hotrodding, as was explained in the original article and in the plans, can drastically reduce the effectiveness of a hybrid's charging and propulsion system), the vehicle performs well. In fact, we're so pleased with the car that we decided to report exactly what our hybrid has accomplished so far, and how we were able to make it achieve such results!

As you read the following figures, keep in mind that our economy and performance tests were all done under actual road conditions . . . unfavorable though those conditions often were. At no time did we estimate or extrapolate range or mileage, or otherwise simulate any kind of driving condition. In short, we stuck to a straightforward, in-use analysis that was even more realistic than that used in the government's EPA mileage tests!

Probably the first two questions anyone would want to ask about the experimental hybrid's performance relate to its fuel economy and range. Such considerations are, of course, directly influenced by [1] the choice of engine used to turn the charging generator, [2] the total weight of the car, and [3] the terrain and driving conditions the auto encounters. As explained in the plans package, the lighter the original vehicle, the more effective the hybrid electric (a term which, of course, refers to the fact that the batteries and the liquid-fueled engine work in combination) will be. Because of that fact, the plans suggest that anyone intending to build a hybrid first select the lightest chassis available . . . then go ahead and set it up as a strictly electric vehicle, and make test runs to determine current draws for that car. Armed with such relevant information, a builder would then be equipped to make the best possible choice of engines ... based upon horsepower, torque, and fuel consumption at a given RPM.

In our case, the Subaru had a total weight—with batteries and 200 amp generating system on board—of approximately 3,000 pounds. Because of our area's terrain (which, as noted above, increases amperage draws considerably over what they might be during operation in a more level area), we found it necessary to add, as per the plans, six extra six-volt batteries . . . to provide additional storage capability. Our prescribed "electric only" testing then determined that we needed—again because of the steep up-and-down grades of most of our roads—an engine with a continuous rating (DIN) horsepower of about 9. For insurance, we finally settled on a plans—recommended 12.5 (DIN) horsepower Lombardini 720 diesel . . . and then set the impressive little powerplant to run at midrange, at which point it produced approximately the 9 horsepower our auto required.

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