You are correct from my observations.  I drive the last generation of
carb Jeep engines and we can disable the emissions controller and
manually tune the engines to get a sweet 25% seat of the pants power
boost with about the same in mileage 'and' still pass the needed
emission 'tailpipe' standards to boot!

A bunch of us have gone from a functional red line of 3500 rpm and 18 or
less mpg to a red line of 4400 and closer to 23 mpg highway in our 80's
Jeep CJ and YJ's.

I have also driven 70's vehicles with no emissions that got great
mileage.  Had a Mini that always got over 50 mpg and V8's that got 20 or
more highway.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos:  Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

In article <dp03i.21$u54.1@newsfe12.lga>,
"Proctologically Violated©®"
<entropic3.14decay@optonline2.718.net> wrote:

As you state it, yes.

Thing is; modern emissions controls reduce emissions by much more
than 10% compared to pre emission control.

Typical 1960s era emissions (no emission controls) were;
HC     10.6 grams per mile
CO      84 grams per mile
NOx      4.1 grams per mile

1978 is the oldest model year I have standards for.
The federal cut points were;
HC     1.5 grams per mile
CO    15.0 grams per mile
NOx     2.0 grams per mile    

2007 Federal cut points are
HC      .41 grams per mile
CO    3.4  grams per mile
NOx     .4 grams per mile

The big three as listed above plus evaporative losses from the
fuel storage plus others...

Impossible to compare since most engines in current compliance
were not available pre emissions control.
A late model 4.6 liter full sized Ford gets way better fuel
mileage that a comparably sized model/engine would have back in
the 60s.

A late model Mustang will eat a 60s era Mustang.

Because the cars sold today have more creature comforts/safety
add ons than those sold 37 years ago and the fact that you cite
two somewhat obscure examples.  A typical 1970 model year car
would have gotten around 15 MPG.  And, as I've shown above,
grossly different WRT tail pipe emissions.

My 1998 Full size Dodge w/3.3 liter engine cracks 30 MPG, 30 MPG
is not unusual for a full sized Buick w/3.8 liter engine.
A newish Corvette probably gets close to 30 MPG driven sanely.

Which also brought us;
better driveability
reduced maintenance
improved reliability

Honda through the '90s routinely produced Civics with 1.5L gasoline engines
that returned close to 40mpg.

My gasoline 1.8L Integra gets a high of 30mpg in the summer, and a low of
27mpg in the winter. And that's with 287K miles and a steady diet of 80mph
highway driving.

The wife's gasoline 1.5L Tercel gets 33mpg summer, 30mpg winter.

So where's the miracle?

"Proctologically Violated??" <entropic3.14decay@optonline2.718.net> wrote:

As someone else has posted it is more like 90% to 99%, maybe more.

No. The pollutants emissions are measured in g/km or g/mile, not in
grams per fuel consumed.

1970 is surely a bad example, because it was before the first oil crisis,
when engines were not particulary efficient, aerodynamic drag was high
(cx > 0.4), etc. Now if you compare cars from the 80s, after _two_ oil
crisis, good aerodynamics (cx was reduced to around 0.3), etc. things
are different.

And the reason for that is because the cars have almost doubled in weight
(I am talking about European/Japanese cars). For instance a Golf GTI, 1st
generation weighted about 840 kg. The current model is around 1500 kg and
so needs (and has) a lot more power to be considered a sports car.

But these days a car needs (marketing wise, not legally) a 5-star NCAP
safety rating and that weights (recent models, for instance from the
Renault Clio and Peugeot 207 have increased in weight some 150-200 kg
and almost all of that was in safety structure).

Another thing that doesn't help is the tendency for taller cars.
Aerodynamic drag is proportional to S.cx in which S is front
surface area and that obviously increases for tall cars. (As a car
designer complained in an interview I read "people are paying for
transporting air" (empty space) "around".)

And yet another thing is wider tyres. Which are a good thing for active
safety, but cost fuel to carry around.

It would be very easy to make a car capable of 3l/100km or better:
start with a 1990 Citroen AX with its 700kg or so, skinny tyres, good
aerodynamic, put a 1.0l or smaller turbodiesel in it and it would consume
even less than the original 1.4l non-turbo diesel (and I had drivers of
those telling me that they got around 3.5l/100km in real life (obviously
driving a bit like in a econo-run)).

Only problem is, nobody would buy it: it is too small (you can fit 4 or
5 adults in it but not very confortably), its NCAP rating would be about
2-stars or less and it would not have the equipment people expect these
days. In fact VW did something like it some years ago. Was it a Lupo or
a Polo ? Anyway, it was marketed as a 3.0l/100km car, but in practice
didn't get that and nobody bought it anyway (it was a bit expensive for
what it was).

In gasoline engines the big penalty for pollutants controls was when
engines went from lead fule without catalysts to non-lead fuel and
catalysts. That was more than 15 years ago (in Europe) and the drop
in efficiency was problably overcome by now with more sophisticated
engine management, 4 valves per cylinder, etc.

But one thing in which pollutants controls are increasing fuel consumption
a bit is in turbo-diesels. For highest efficiency you want all the fuel to
be burned in one go, but for reducing pollution recent engines do as much
a 5 injections in one cycle. And the particle filters restrict the exhaust
and some fuel is used to burn the soot in that once every 1200 km or so.