carburetors that allow you to drive 1000+ miles to the gallon

Car computers are very variable. Nowhere is this better illustrated, than on Top gear a year or two ago, when the presenter drove an Audi A8 from london to edinburgh and back on a single tank (thats around

400 miles, in a 4l V8 twin turbo diesel). Not only did the computer say he was low on fuel too early, but that he'd completely run out around milton keynes, an hour or so short.

low a speed as practical is not true. It comes from keeping at the peak torque point. I used to do economy runs in my old volvo, its most efficient speed was 58mph, because that was how the gearing worked out to be the engines peak torque point, in the top gear. now, you could actually cheat a bit and extend it, by going right behind a HGV (semi for the americans) and holding steady at their limited speed 9usually about 62-63mph). I think i managed to get about 55-60mpg from my volvo in this way, thats in a 15yo car, with 4 passengers. Peak torque rpm point is always the point where the engine works most efficiently. thats how come its the peak torque point.

There's more to it than that, gearing and powerbands make a difference. Fuel consumption's finite, it'll take a certain amount of energy to maintain any speed. Reduced wind and rolling resistance will reduce the energy needed, then it's just to how efficient the engine is at that RPM in converting fuel to energy.

I used to get 34MPG at 70MPH with a 1962 Oldsmobile F-85 with a 215 V8 and a 4bbl carburetor.

Most cars today can't get that sort of mileage with fuel injection and half the cylinders. So much for 40 years of engineering.

I think most would agree that California has the worst of these.

In February, 1998 in San Diego the average was $1.29 according to

Cheap fuel was a largely ignored economic factor through most of the

90's. I remember news stories about gasoline prices below a dollar in GA.

I don't personally recall anything less than $1.09 locally, but we only have three supplying refineries and two companies running those, so competition's not keen.

Computers in carbureted cars and older injected cars have a lot of variables (especially analog transducers to measure air or fuel flow), but the computers in modern injected cars are very accurate - more accurate than calculating on the basis of one or two fill-ups. The ECU knows exactly how long it is opening the injectors (how many crystal-controlled clock cycles), and exactly how often. The distance comes from the VSS in exactly the same accuracy the car's odometer has, so the only variables are fuel pressure and injector lag. Prius owners have reported errors ranging from 2% to a shade over 5% optimistic. (Interesting that none report their displays being pessimistic.) I don't recall any saying their display was 10% or more off the actual unless they were comparing a single tank based on when the pump clicked off.

Mike

Any fuel has a certain amount of stored potential energy. Burning that fuel can release that much energy and no more. It takes a given amount of energy to move a given amount of weight. A fancy carburetor can't get more energy out of the fuel than it already contains, or reduce the amount needed to move the car.

Usually you get a substantial amount less power out because of improper combustion, and improved combustion can make for more efficient energy production, but not THAT much more efficient.

CHAMP cars (the open-wheel racers used by CART) use a 2.65 liter V-8 (8 cylinders, but barely more displacement than my Accord) that get around

750hp. They burn straight methanol tho...