With any engine, gas or diesel, one major step in reducing emissions is to add an oxidation catalyst (often called a catalytic convertor). So the major difference between the Umwelt diesel and a regular VW turbo diesel engine is that the Umwelt diesel has a catalyst. But they didn't stop with just adding a "cat." The VW turbo diesel engine has a thing called a "boost enrichment device" attached to the injection pump. Its purpose is to supply extra fuel to the engine when the turbocharger is making a large amount of boost (i.e. full-throttle acceleration, or going up a steep hill). But often the engine can't burn all of this extra fuel, and some of it ends up going out the exhaust pipe.
If this unburnt fuel in the exhaust was allowed to enter the catalyst, it would damage or even destroy the catalyst -- causing VW's efforts at reducing emissions to (quite literally) go up in smoke. So the second modification VW made was to simply remove the boost enrichment device. Of course, this reduces horsepower a little bit, but the turbocharger is still there so the Umwelt diesel is still more powerful than the non-turbocharged VW diesel engine. And the Umwelt diesel's turbocharger has the same maximum boost pressure (9.6 psi above atmospheric pressure) as the regular turbo diesel, so the turbocharger can do the same amount of work; but without the boost enrichment device, there is less fuel reaching the Umwelt diesel engine at full throttle.
These are the two main features that distingiush the Umwelt diesel engine. Otherwise it is pretty much mechanically identical to the regular VW turbo diesel engine. In the real world, these modifications do seem to work very well; in most driving conditions, the Umwelt diesel emits no visible smoke from the exhaust pipe, at least when the engine is warmed up. In fact, it is clean enough that VW was able to sell the Umwelt-powered ECOdiesel in California, a state whose tough emissions regulations prevented VW from selling regular non-Umwelt diesels there since the mid 1980s.
VW's Umwelt diesel engine was actually made in two forms -- a 1.6-liter
version and a larger and more powerful 1.9-liter version. However, only the
smaller 1.6-liter version was officially called the "ECOdiesel" and sold in
the USA. The 1.9-liter version was sold in Canada and Europe in 1993-1997,
but never made it to the USA. Conversely, the 1.6-liter ECOdiesel was only
sold in the USA, and never made it to Canada or Europe.
The 1.6L Umwelt/ECOdiesel Engine
A picture of the 1.6L Umwelt diesel engine as it is found under the hood of a
1991 Jetta GL ECOdiesel. Click to enlarge!
|1. Fuel filter|
2. Air filter box
3. Oil filler cap
4. Injection pump
6. Oil dipstick
7. Oil filter, with oil cooler (silver box above oil filter, partially hidden by AC hose)
8. Brake fluid tank
0. Coolant tank
Of course an engine is nothing without a car to put it in. So VW decided to put the ECOdiesel in the most popular Volkswagen in America, and in the same car that was also previously sold with diesel and turbo diesel engines... the Jetta. But VW's timing was a bit unfortunate; the Jetta ECOdiesel reached U.S. dealerships in early 1991, at a time when sales of the Jetta/Golf/GTI-series cars were slowing down, as they were due for a re-design, which finally came in 1993. Also, with gas prices remaining relatively cheap during this era, diesel-powered cars were not very popular; in 1991, only eight percent of Jettas had diesel engines, whereas over 50 percent of all VWs sold in 1981 had diesel engines!
Aside from the engine, Jetta ECOdiesels did have a few minor differences from
the gas-engine Jetta. Following their tradition, VW did not give the Jetta
ECOdiesel a tachometer, but instead a large analog clock to fill up the space
in the instrument cluster where the tachometer would have been. Red marks on
the speedometer give you a rough guide as to what speeds to shift gears. All
Jetta ECOdiesels were sold in the GL trim level, so the car's name officially
becomes the "Jetta GL ECOdiesel", as evidenced by the badging on the back of
the car. And perhaps to make it more attractive to potential buyers, most (or
all?) ECOdiesels were sold "fully loaded", equipped with Option Package Q8,
which consisted of air conditioning, a manual sunroof, cruise control, and a
six-speaker "Heidelberg" audio system.
The Jetta GL ECOdiesel was sold for two "model years", 1991 and 1992. But in
both cases it did not enjoy a full 12 months' stay on the showroom floor. The
ECOdiesel first arrived in the spring of 1991, and a total of about 750
ECOdiesels were sold in the 1991 model year. All of them were manufactured in
VW's home factory in Wolfsburg, Germany, following the tradition of previous
diesel-powered Jettas which were also made exclusively in Germany. 1991-model
Jetta ECOdiesels were available in a full spectrum of colors, including green,
blue, gray, white, red, and black -- all with gray velour seats and black
Unfortunately for the ECOdiesel, German production of A2-series Jettas stopped
shortly after the 1992 model year began in mid-1991, as the factory was
switching over to production of the new A3-series Golfs and Jettas. So, if
VW's records are correct, only 47 -- yes, that's forty-seven --
1992-model Jetta ECOdiesels were made! Although the exact color distribution
amongst these 47 cars is unknown, most of them are black, with a few gray ones
and a few red ones.
Base price (MSRP): $11,230
Destination charge: $340
You may ask, how do I know it's a 1992 model ECOdiesel? Well, of course you first have to make sure the car you are looking at is an ECOdiesel. The easiest way to do this is to look for the "ECOdiesel" badge on the back, underneath "Jetta GL". Once you know the car is an ECOdiesel, you then have to check the VIN number to see if it is a 1992 model. The VIN number is found on a small plaque on the driver's side of the dashboard, and can be seen through the windshield from the outside. It should be something like this: