Geo Metro Truck?

[Christ]

Probably a better idea.

BTW - if you wanted to do that with a non-driven Metro, you can retain trunk space in the front by using a 600CC bike frame/motor/tranny/wheel for the drive. The whole setup could be easily removable and the front triple tree bolted back on for use as a motorcycle as well, and the front of the car, where the old engine was, could be boxed in and used for a large trunk. Bike for when it's just you, Modded Metro for getting groceries or parts for other projects.

Could be made to take about an hour to convert back and forth.

[Sorrow Six Star]

^^ I would love to see that... a metro with a Busa in the back...

[Frank Lee]

This would help out immensely on it's own, due to rolling resistance being lowered by 25%.

I wish it was so, but I don't think it works that way.

[Christ]

4 tires making rolling resistance for a total of 100%... remove 1/4 of the tires, you remove 1/4 of the rolling resistance (in stupid math).

If you really want to get technical, you're not really losing 25%, because you're now placing more weight on one tire. You might in actuality lose only 20%, but it's still significant.

[Bicycle Bob]

Rolling resistance is almost linear with load. A trike per se has no advantage that way, and also looses by making more tracks in sand and air.

[Christ]

So load isn't decreased when you lose a wheel and all the weight associated with it, including the 20%+ of the chassis you're removing to taper the body work?

[Frank Lee]

Back when I wanted to do a trike conversion to my Tempo in the worst way I came across the math and calced it out. Projected r.r. reduction was so small as to be almost pointless.

My project would have lost maybe up to 80 lbs from the deleted wheel/suspension- which doesn't do much- and the r.r. like Bob says has more to do with load. I'd expect some gain from elimination of scrub on one end but absent any testing of that theory, my sources say that factor is very negligible too.

I wasn't going to mess with trying to taper the body. For one thing it would be difficult to achieve a nice curve inwards in plan view. For another I have my doubts about the effectiveness of extreme boattailing in plan view in the real world due to... get ready... the dreaded CROSSWINDS.

[Christ]

My suggestion was streamlining the three wheeler, though. The initial RR loss would probably be insignificant until the extra weight of the chassis was shed, but as the project were to progress, it would take a better chunk of the RR away as well. IF you've got less weight on a tire, it's bound to have lower frictional loss.

On a Metro, I don't think the wheel and associated parts even weigh 80 lbs, honestly. I could be wrong, though.

[Bicycle Bob]

If your trike comes out lighter, that reduces RR. Deleting a wheel per se has no major effect. A three-legged table is potentially a more efficient structure than one with four, but with vehicles, that increment is swamped by the need for a wider stance.
BTW, bearing friction is almost vanishingly small compared to tire drag, often as low as .001 X the vehicle weight.

[Frank Lee]

My calcs estimated the stability of a trike Tempo to be comparable to that of a Dodge MaxiVan. Sure, some stability degradation vs stock but nothing unmanageable. Some calculated stability was regained by a simple mild lowering as I've done on my black car. So the front track wouldn't need widening.