Do they measure automobile pollution by the mile or by the gallon?
I purchased a 1986 (4-on-the-floor?) diesel VW Golf that went 54 miles to the gallon of fuel. When that died, I purchased a 1999 5-speed Jetta that went 48 miles on a gallon of diesel. I just purchased a 2014, 6-speed, diesel Passat that gets 43 miles to the gallon. (note: I considered a slightly lighter Jetta this time, but the MPG was the same. )
Despite newer technology and more gears, I consume 25% more fuel than I did in 1986. The stock answer I get is “pollution control”. Did the amount of pollution go down by more than 20% (per gallon)? I didn’t think 1986 technology was that bad. What are they concerned about? Even under the best of circumstances, I don’t think they can reduce CO2 output on a per-gallon basis, so my CO2 output has gone up 25% per mile.
The CO2 emissions from your car are inherent to the combustion process and are directly tied to your fuel consumption. In fact, that’s how the EPA measures fuel consumption-- they run a car on a dynometer and run all the exhaust through a device that measures the amount of carbon in it.All the other stuff coming out of the tailpipe has been traditionally measured by percentage. Even if your newer car is cranking out a bit more carbon, it’s emitting massively less carbon monoxide, particulates, NOxs, etc.
Also do note that the EPA has revised how they rate MPG on cars a few times since 1986. Just for fun, I plugged your three cars into fueleconomy.gov and both the '86 Golf and your '14 Passat are rated at 35 MPG combined, while your old '99 was rated at 37. The new Passat is also rated at 43 MPG highway whereas the '86 Golf was only rated at 40. I find that when waxing nostalgic about old cars, our recollections are usually either way over the mark or way under.
The OP didn’t mention the EPA estimates for those cars, but seemed to be reporting his actual observed mileage.
I have never had a car that didn’t get better mileage than the EPA estimate, except for a 1985 Olds Delta 88 that, near the end of its life and experiencing engine problems, was getting about 14 to 17 mpg.
I have been hearing people make this same complaint since the 1970s: gas mileage getting worse on a comparable car, and being told emissions control was the cause. I know people who disconnected their emissions control gear because of that (I’m told cigarette filters block the vacuum lines nicely.
For my part, I had a 3 ton 1975 station wagon in 1988-1991 that was getting 24mpg city, 28mpg highway, and the sniff test said there were no unburned hydrocarbons in my exhaust. It always passed emissions testing with flying colors.
I cannot understand how an suv that is 3 decades newer and 1 ton lighter can’t be doing better than that, but a lot of them aren’t.
Kanicbird has the answer. Your '86 had a 68 horsepower engine and weighed 2072 pounds, the '99, 90 hp and 2679 lbs., '14 has 140 hp and 3393 lbs. That’s a 1321 pound and 72 horsepower difference between the '86 and the '14.
Look at it this way- your '14 engine has over twice the hp as the '86, and the car is about 39% more massive than the '86. Try imitating the '86 performance level in the '14, and you just might get the '86 mileage.
Yep, people have been making that same complaint pretty much since the invention of the automobile. The root cause is that people’s memories aren’t very good and they conflate the best ever mileage they got with what they typically got. The EPA ratings aren’t perfect (I usually beat them too) but they’re a good way to make an apples-to-apples comparison.
Don’t forget that fuel formulations have also changed over the years. I don’t know about diesel, but gasoline current blends are less polluting but also produce less energy than gas of old.
Of course, one corollary to the “more power” point is that even if the two cars do the same in a similar driving cycle (as the EPA numbers suggest) it’s very likely you’ll be driving the autobahn-worthy '14 Passat a lot more spiritedly (shall we say) than an excruciatingly slow '80 diesel VW. I used to marvel at how my air-cooled VW project car got better mileage on road trips than my allegedly modern Honda daily driver until I realized it might have had something to do with the Bug not really liking to go much over 55 MPH.
Assuming constant engine efficiency, CO2 output scales with engine energy output. CO2 hasn’t historically been a direct concern for the EPA (at least not until 2007); the EPA measures vehicle fuel economy, but CO2 has only been indirectly regulated via Corporate Average Fuel Economy rules.
For the EPA, the pollutants of interest for passenger cars are:
HC = hydrocarbons. Basically unburned fuel. These are worst during a cold start, when fuel vaporizes poorly and/or combustion gets more severely quenched near cold combustion chamber walls (and the catalytic converter isn’t warm yet). But even in a fully warmed-up engine, there is still some HC coming out of the engine.
NOx = oxides of nitrogen. These are created in when oxygen and nitrogen are expose to high temperatures, e.g. those encountered during combustion. Lean combustion makes more NOx because there’s more oxygen available to combine with the nitrogen. High power output also makes more NOx, because of the higher temperatures. This is a big problem for diesel engines, which always operate very lean (compared to gasoline engines).
PM = particulates. These are tiny particles of carbon, either single or aggregated, produced during combustion of rich mixtures. You don’t get much of these from gasoline engines, since they tend to be very well-mixed, but they’re unavoidable from a diesel, since diesels have very inhomogeneous fuel-air mixtures. PM ranges in size from nanometers to several microns (much bigger than that, and they just fall out of the air). PM2.5 is particulate matter that is less than 2.5 microns in diameter and is particularly troubling because it tends to get past your respiratory defenses and deep into your lungs - where it then deposits and releases whatever carcinogenic crap it adsorbed along the way (HC’s, PAH’s, benzene, etc.).
Regulations on vehicle emissions have tightened up in a massive way over the past couple of decades. Permissible NOx emissions today are about 4% of what they were 20 years ago. PM? about 10% of what it was. In other words, since 1994, diesel emissions have gone down by 90-95%. A lot of this has been achieved with exhaust aftertreatment, but some of it has been dealt with by changing the way the engine itself operates, and diesel fuel economy has suffered because of this. For example, there is an optimum timing for diesel fuel injection (relative to piston top-dead-center) that will deliver best fuel economy. But if you inject at that time, you end up with very high combustion temperatures - and you make a lot of NOx. So late-model diesel engines tend to use retarded injection timing to keep engine-out NOx levels down, which results in less-than-awesome efficiency. Similarly, to keep PM levels down, diesel engines use a lot more turbo boost than they used to (so they can run with a lot of excess air). That turbo boost doesn’t come for free.
And, as has been noted, cars these days are typically heavier and more powerful than they were 20-30 years ago. Engine efficiency is decreased when operating at a small fraction of its max power output. So if you’ve got a car that cruises with x% of max power output, and you put in an engine with double the power capacity, now it’s cruising at 0.5x% of max power output; it will almost certainly consume more fuel at cruise (not to mention the thrill of jackrabbit launches when the light turns green).
in 2007, ultra-low-sulfur diesel fuel was mandated for passenger cars and many other diesel vehicles. This enables the use of exhaust aftertreatment technologies that allow major emissions reductions, but the production process for ULSD fuel lowers its energy density by about 1%. This means the use of ULSD fuel would be expected to account for about 0.4-0.5 MPG of the fuel economy drop the OP observed between 1986 and now.
I think it’s worth re-iterating that the OP’s new car has TWICE as powerful an engine and is one and half times as heavy compared to the OP’s oldest car.
That’s going to make way bigger a difference than a few percent here and there because of emissions controls.
Also because that’s what people want, it is seen as a improvement to have more room. People when they buy a new car might consider buying the same model as they have, they like to see it in a ‘upgraded’ form, so that leads to a larger,heavier and more powerful vehicle. If the prospective buyer buys one that is downgraded in those categories the buyer may be disappointed, so better to scale up and start a new line of smaller car models.
That hit me when I saw the IIRC Honda Civic, what used to be a very small car is now pretty large and roomy - over the years it has grown up
The Subaru Outback likewise used to be a raised AWD stationwagon and has crossed over to full sized SUV in it’s latest form.
