Why is designing a 40 MPG car called "Rocket Science"?

Dodge did the same thing in the mid 70’s with the Dart “lite”. No fooling, it got 30 -35 mpg in 1975, 6 passenger car. Rocketman

My own conspiracy theory:

I sincerely doubt that the big three, GM, Ford and Chrysler are purposely keeping the fuel consumption on their products high. I just think that fuel was and is too cheap to consider alotting a big amount of their R&D money towards eco-cars. I do not see capable conspirators , I see a lot of economists at the top with lack of vision. Instead of sticking money into engine research , which is a high risk business. One would spent money on the cars new styling. A case in point, the Ford 92 LX had a carbeurator in the 90s. Most people will think, what is wrong with that? Well to keep it short, the modern fuel injector has a few tricks up its sleeve to reduce fuel consumption. One of them being, shutting of the fuel flow while decelerating with the foot off the gas and in gear. I remember one of the ford people, giving examples why the hybrid would not sell. This was the time when the Prius was introduced to the market. Here are a explanation, why it seems the combustion engine consumed more fuel after the introduction of emission laws. I am guessing in the old days, that the most motors were running on a lean mix, which means the ratio of air to fuel was such, that the fuel had more air than it needed to combust. This is mostly positive, this means that most of the fuel will have a chance to combust (burn) and next to no unburned fuel to be purged. Ah but then there is the excess oxygen which usually does nothing in our ambient temperatures, but in the high temperatures of the cylinder in goes into a unholy bond with the ample nitrogen and we get different types of nitrous-oxides. (If you look at your emission sheets it is NOx) Needless to say it is a toxic gas, it is responsible for forest rot in Germany etc. So all this had to be sorted out by changing the air fuel mix and then came the brilliant US-invention the catalytic converter. Back to the point, real life is too complicated to have few people to keep ever thing in check.
Here are a few perfectly innocent reasons the diesel did not make it big in the US. The first and utmost important one is the California emission standards, which I applaud. California is the biggest car market and if you can not sell your car there, you have already lost a considerable chunk of the market. To the reason, why diesel can not achieve clean emissions, the biggest one being the sulphur content in US-Diesel, which has be sorted. To the argument the big three sell Diesels abroad and not in the US. This is I find the saddest part. I suspect the big three have no small compact diesel engines of their own. These engines are bought in. The Jeep uses a VW TDI, Ford has psa engines (Peugeot) and Chrysler uses Mercedes engines which can be bought in the US as the Liberty CRD. I have no idea if GM has its own diesel engine.So I think it makes it hugely expensive to import the engines just for the small domestic market.I guess the big three have been sleeping though the compact engine research. As an example of how far foreign firms have advanced, VW have a gas engine which has a displacement of 1.4 Litres and 170 HP. The golf gets 33 mpg with it and it is very quick.Toyota is also a a prime example of high risk research, which paid off. Who knows maybe the big three will notice that you can not build your core business around muscle cars a la charger (it does look sweat) and concentrate on boring small engines.

I wouldn’t want a carbon fiber or other composite framed car because of failure mode. Metal fails via plastic deformation, stretching (and thus absobing energy) in an impact, wheras composites just snap.

A frame made of 7075-Al, however, would be a verry nice thing!

Did yours have the Volkwagen engine? Early models used the Rabbit engine and got great gas mileage. Later ones with Chrysler 4 banger were less frugal.

I agree that there’s no conspiracy.

The “big 3” have spent billions over the years on eco-cars, but they are risk-averse. And putting them on the market involves risk. they’d rather spend the money (millions, actually) putting a “known commodity” on the market than something new. Chrysler, when it was under Lee Iacoca, took risks with eth Dodge Ram design, the Cruiser, the 300, and others and it paid off big.

Old cars ran rich. The fuel droplets were a lot larger from carbs because they worked via a low pressure-differential feed, using variations in the lateral sidewall pressure of the venturi caused by changes in velocity of the airflow stream to draw the gas through the feed orafice. Modern injectors use a high pressure differential system, high pressure spraying through an orafice the volume controlled by changing spray pulsewidth. That provides much more accurate and smaller fuel droplets which burn more completely in the limited time spent in the chamber. That means more of the gas’ energy is used, less gas is needed, and fewer unburned hydrocarbons get expelled. Remember that only the surface of the droplet burns, only those hydrocarbon molecules that are in contact with oxygen. In order to get sufficient power out of the larger droplets, the old carburated engines had to run richer.

Interesting comments about NOx. Forest rot in Germany? Really?

In my opinion the diesel did not make it big in the U.S. because they’re smelly, dirty, and noisy. They also produce much more NOx, HC, and CO than gas engines, but in truth if they were not smelly, dirty, and noisy people would have bought them anyway.

GM tried years ago to make a diesel out of a gas V8. It was a disaster of epic proportions. They now have diesel truck engines, but I don’t know the details of them.

Personally I think GM will continue to be risk averse. I hope I’m wrong.

Pretty cool description of the inner workings of an engine. I guess the reaction surface increase, through smaller droplets and greater dispersion, is the real advantage of the fuel injector over the carburettor .I thought I read some where that some one is introducing direct injection to the gas engine or this has been done. Yes I have to agree with you Diesels produced more NOx,HC, SOx and CO. This problem is supposed be solved with the new bluemotion diesels. It might be a different marketing name, some thing blue. One thing is not true any more, they ( Diesels) do not smell, they are not as loud and with the new particle filter, it should not be putting out soot like the first steam engine from Watt or Stevenson. If you ever open a modern diesels hood, you should see how much stuff they have put in to the car tp muffle the tractor sound. FYI the common rail diesel is supposedly less rough than the conventional diesel. Oh when I wrote forest rot , in the 80s NOx combined with rain made acid rain. The correct term is forest dieback.

GM builds lots of small Diesels - in Asia and Europe. They will bring them here in a few years.

Seriously, the Honda CRX HF from the late 80s early 90s got and continues to get 60mpg hiway. Just as efficient as the Prius, only without all those batteries to lug around!

I BELIEVE THAT ALL NEW CARS MANUFACTURED IN THE USA SHOULD BE 6 SPPEED MANUAL TRANSMISSIONS…FOR BETTER FUEL CONSUMPTION AS THEY DO IN EUROPE…AUTOMATICS WILL BE AVALIABLE TO HANDY-CAPPED ONLY…
THIS IDEA CAN BRING MANY CARS TO 30 PLUS MPG…ITS A GOD STARTING POINT IN MY MIND…

Modern automatics are more fuel efficient; a computer is much better at optimizing shift points then a human.

I just spent a week at the SAE World Congress in Detroit and the most prevalent theme for ALL of the automakers was increasing fuel economy. The problem is not so much on the technology side, but more on the cost side.

There are numerous technologies available today for increasing fuel economy, but what the auto industry has found is that these technologies are currently too expensive, and most consumers are not willing to shell out more money for a more fuel efficient car. Case in point is hybrid technology; the only successful hybrid, from a sales and marketing standpoint, is the Prius. Why? Because Toyota designed the car to look and operate significantly different than non-hybrid models. People are willing to pay the higher cost for the hybrid technology if it comes with new ?image? as well. The hybrids such as the Escape and Civic look and drive almost identically to the non hybrid models, but have a higher price tag, and the vehicles sales and market research demonstrate that this approach does not work; the general public is simply not willing to pay for it.

Until the cost of higher fuel efficient cars can be reduced, or the auto industry can change the mindsets of the average consumer (Ford has been trying this approach with their Escape marketing), larger fuel efficient cars will be a very slow evolution.

From the point of view of the domestic manufactures, very few people are willing to pay a premium for a domestic regardless of fuel efficiency. At this point, their market is trucks, SUVs, fleet cars, and very low end econo-boxes. There are still a few folks who will buy overpriced retro-car (mustangs, camaros, chargers, etc.) and weird stuff like the current Cadillac, but not enough. They have spent the last 40 years getting themselves into this market ghetto (and they’ve lost at least one generation of customers), they are not getting out overnight (if ever).

You are correct that the Prius is mostly a fashion statement at this point (most people use the name Prius as a generic term for hybrids) and every celebrity is bragging about their new Prius. From a technical point of view, it’s probably a dead end but toyota should win some kind of marketing award for selling these things in large numbers. I also assume that toyota will be smart enough to get out before the fad ends in a few years. The domestic have to be careful that they don’t arrive just as the party is ending and everyone else is getting into the next thing.

Thanks.

Yeah, they’re developing direct injection for gas engines. Since it would have to take up area that could otherwise be used for moving fluids in and out (valve space) and would thus (I would think) have to compromise the capacities of the valves to feed and evacuate the cylinders, I can’t visualize its benefit over port injection. Diesels use direct injectors, but they don’t need spark plugs, so they can effectively use what would have been spark plug area for valves.

The new diesel systems have substantially reduced carbon monoxide and unburned hydrocarbons, and of course carbon clouds, but since they operate with compression and cylinder temperatures much higher than gas engines they really can’t get the NOx levels down with any kind of mobile system. Diesels simply cannot currently meet the same emissions standards. I agree that the acoustics engineers have done great deeds with quieting the noise down.

Because diesels are not required to test, there are also millions of them on the roads that are running filthy.

My feeling is that when diesels are required to meet emissions requirements (I would accept ones modified to accomodate their inherant weakness, NOx), then I’ll be less opposed to them.

All is not lost for the US-Car manufacturers. A good example for an image turn around is the skoda. Skoda in the 90s had the east block reputation and even after VW took over, these just had the image of east block depression. Some how they managed to turn there image from east block to quality cars. The resale values are better than VW. I guess producing cars with workmanship better than that of VW, did the trick. If the Saturn Astra is build as well as the Opel Astras, I can see GM changing one of its images in the near future. Loafer makes a very good point about fuel efficient cars being too expensive.Practically a diesel is generally 3000 $ more expensive than the gas equivalent. You can drive pretty far on 3000 $ of gas. Just a small rant about those Hollywood stars and there silly Prius. Driving Prius means nothing if you take a private jet any where. At least 400 gallons kerosene from LA to Vegas, now how are you going to reduce you carbon footprint with your silly Prius, Hollywood jack ass. People do not get me wrong, drive a Prius if you must, just do not expect the Prius to cancel out the private jet, that`s all.

Jeez, so many of us want the government to force the rest of the population to be exactly like us. Be careful what you ask for lest the people who decide what the rest of us are going to live like end up being tofu eating, patchouli reeking, bicycle riding, vegans.

I’m not replying directly to this post, but just putting my 2 cents worth at the end of this discussion. I just bougth a smart about 4 weeks ago. I now have about 1600 miles on it. I ordered this a year ago, before gas prices were as terrible as they are today. That seems to be the only thing people are talking about. Well, of course the smart gets good mileage (35-45mpg for me so far) but it’s about so much more than that. I just think it’s a hoot! With the goofy transmission and underwhelming power, you actually have to drive it! Sometimes it’s better in the auto mode, sometimes it works to keep it in the manumatic mode, and hold a gear while you’re moving through traffic, or coming up to a curve or hill. It’s not just another appliance, but takes some learning and paying attention. It’s certainly not for everybody, but I just love it. And at 6’3" it’s one of the most comfortable cars (great seats and head and leg room) I’ve ever driven. If you just want cheap transportation, and good gas mileage, there are plenty of cars out there that will offer that…Honda, Toyota, Scion, Hyundai, Kia, Aveo to mention a few. But NONE of them have the style or uniqueness of this little smart. In fact, please don’t buy one…it’s fun having something hardly anyone else has. (And the environmental friendliness is a bonus.)

Designing or building a car that exceeds 40 mpg is super simple. But would you drive it? That’s what drives what car manufacturers offer.

Picture this-

RX-7 body. 1st gen or 2nd gen. you take your pic. Either way the drag coeffiecnt was around .29.

Now take a 1.0L 3 cylinder motor that in it’s last version strapped to a non- aerodynamic Geo Metro got an honest 40 mpg. Update the motor with current electronics including real world direct injection (not the TBI it had) plus instead of SOHC, make it a DOHC. Now you’ve bumped the hp up 8-15 hp and increased the effieciency by leaps and bounds.

You might go 0-60 in 12 seconds or so, and with the lower drag, higher output motor, you could climb hills adaquetly.

Fuel economy would roughly be 45-50 mpg. You could offer a diesel option- the 3cyl that VW has tested in Europe that gets 70 mpg in the city.

BUT- would the masses buy it? Probably not. Why? Because the US is full of vein sob’s. Your car is a status symbol and their attitude is “I wouldn’t be caught dead driving that thing I don’t care if it got 100mpg”

The issue has nothing do do with current vehicle weight, or electronics. The vehicle is 100% feasable, but it won’t make manufacturers any money cause nobody will buy it.

The issue has nothing do do with current vehicle weight, or electronics. The vehicle is 100% feasable, but it won’t make manufacturers any money cause nobody will buy it.

Very true, there is no incentive to buy that car with the current cheap fuel prices. If fuel prices doubled, I might consider it (actually I wouldn’t consider it, but plenty of people probably would).

I agree that the technology for 40 mpg cars is already here. Way back at the beginning of this thread I cited hybrid technology and ultralight composites.

The reason people wouldn’t buy them is simply the cost. Hybrids cost more, and converting manufacturing facilities from working sheetmetal to creating composit panels would be expensive. Making parts from sheet steel and spot welding them when the production line is already set up to do that is far cheaper than converting the entire line.

In short, the bulk of the marketplace simply won’t pay the extra price for high mileage vehicles. And in all honesty I’d rather see them begin to look for ways to REDUCE the price of new vehicles. Stop adding bells and whistles and come out with a modern, cheap, basic, usable mode of transportation. Before Tata invades the market with their rolling rubbish barrels.

I agree the U.S. market needs a good cheap basic vehicle. I don’t know who will provide it, but I’m fairly certain that it won’t be the “big 2.1” (they’ve been demoted again). It may well be Tata, I remember when we all laughed at toyota/honda.