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

electrical-wiring

#1

My parents had a Sprint when I was in high school and that car (although small) got 42 miles to the gallon all the time. If we had technology to do that 20 years ago, why is it that the “Smart” car only gets about 40 mpg and it is being billed as this miracle? At least in the Sprint you could seat 4!



I do not understand…


#2

It’s an easy answer: weight. New cars have been increasing in weight at a rapid pace since the 1980’s because of increasing demand for safety, electronics, new features, etc. For example: my 1988 Volkswagen Golf GTI weighed in at 2250 pounds, now a 2008 GTI is 1000 pounds more. You can’t add thousands of pounds and not expect mileage to fall, new efficient engine or not. Thats the basic reason.

The Smart car is a case of a car actually being underpowered. Since you frequently have to apply the throttle liberally in traffic the mileage isn’t as great as it could be with a slightly more powerful, yet less taxed engine. Keep in mind though that goverment fuel mileage ratings changed across the board for 2008 so all cars seem less efficient now by the numbers.


#3

There are more standards that have to be met. New cars need airbags, side impact beams and the like. New cars also need to meet strict emissions standards; which requires electronic engine controls and such. Most new car buyers demand air conditioning, a cd player, power windows and locks, and a multitude of comfort and convience features. All of these things add complexity and weight. If you got into an accident in a Sprint/Metro, it is a good possibility that you would not survive. The Smart is much safer (by clown car standards). But as mentioned before the extra safety and comfort add weight which costs fuel economy.


#4

Well I wouldn’t write off the sender’s initial comment. In 1964 I used to take a '60 Rambler to college. 6 of us with suitcases would be the transport… NO one too small. Got 30 MPG then. 6 cyl, standard, overdrive. OK I’ll give the extra stuff on the car 5 mpg. So I stand with IngridAC to say why can’t thye get 35 mpg? I think a bit more of political economics is involved in this also.


#5

Weight is a factor, as others have mentioned, as newer cars have crash protection and airbag systems that your parents didn’t have, however the truth is that the technology does exist. The Smart is a poor example because it is underpowered…my 2005 Corolla got 38 mpg legitimately.

The technologies I’m alluding to are hybrids and the use of ultralightweight materials. Hybrids are becoming common, but they do cost more, and ultralightweight materials are currently too expensive for all but the exotic cars. There is very little extra that can be squeezed out of gas engines.

In short, the technology exists but not affordably to the average buyer.


#6

I don’ know who’s billed the Smart car as a miracle of fuel mileage. It’s selling point is it’s size and they have been around for years in Europe selling with that angle. I think many Americans assume that because they don’t see ultra efficient cars for sale here it must be a conspiracy. There’s many fuel efficient cars sold in Europe that achieve very high gas mileage, but they usually never saw the light of day here because they DON’T SELL WELL here. Micro turbo Diesel cars leave the U.S. public scratching their heads. At least in the past anyway.

As for the folks here who don’t feel the weight issue is enough to justify current mileage, you’re right. There’s also the issue of engine output. Today’s cars put out massive amounts of power, and efficient or not, when you call on 260hp hp in your Accord or 400 hp in your BMW the gas starts getting sucked down quick.

One last point, I think sometimes people have an overly rosy memory of the gas mileage cars achieved in the 1960’s. I think sometimes people forget that 6-9 MPG was common in a lot V8 powered cars. There were efficient cars, but 30mpg was quite an achievement back then.


#7

I personally hate new cars and certainly would never buy a Prius or any other hippie roller skate that people are being forced into buying due to high gas prices.
1960 Falcons and Comets get very good mileage and still have looks.They are also made of metal.
I dont think fuel economy should be the issue,I think gas prices are the problem.
There is no need for fuel to be almost 4 bucks a gallon.
We have plenty of gas,this is fact,but all the hippie tree huggers are pushing as hard as they can for these toy cars and alternative energy vehicles.Its all an ego trip,so they can feel they are “making a difference”.
Unfortunatley it is a difference for the worse.
these feel good hippie types are very hypocritical though,Overpopulation is a huge problem which is never addressed as it isnt politically correct,yet scientists have pointed out repeatedly how insanely our population has exploded since the late 50’s.
Think about it folks,do we really want to live like the red chinese,no room to park,everywhere you look its crowded,no privacy?
What about the destructive impact all these extra children are having on the enviroment?
Less people on the earth = less people on the road=less traffic jams,less fuel consumption,less garbage in the landfill and a higher quality of life.
but people will not learn.
To me a car isnt just a device to haul me from one place to another,but rather a thing of beauty.something that is fun and enjoyable to drive,we used to love our cars.
It disgusts me to no end that a very small but vocal segment of society thinks they have the right to instigate moronic laws regulating what type of vehicle and fuels I am allowed to use.
This Global Warming scare is a crock,it is psuedo science cooked up by Al Gore to make money.(carbon credits,yeah right!)
It has been proven that global warming is cyclical.All the nonsense in Gores scare manual has been debunked with cold hard facts.
Our planet has been through an Ice age long before the advent of mans industrialization,yet there are uneducated throngs of people scared out of thier (limited) wits buying into all this carbon credit b.s. and running around like mad hens trying to force Cfl’s and wind up toy cars on us all!
The mass majority of people dont want toy hippie mobiles.thats why Mustangs and Vettes and trucks still exist and account for the MAJORITY of vehicle sales.
So fuel PRICE should be the issue,NOT Miles per gallon.


#8

I think 40 mpg is not rocket science, the problem is gas being as cheap as it was made such a vehicle undesirable, and therefore not marketable. If gas prices continue to rise I am sure you will see 40MPG cars in the future, its just may take a couple years for these cars to get to market.


#9

I agree with the others, it’s simply a trade off between mileage, performance, emissions, style, safety, and cost. You may be able to find some of them in the same car, but not all of them. As long as we have cheap fuel, mileage will not be a priority.


#10

Food for thought - and its not about “tree hugging hippes” with “ego trips”:

http://www.theyrule.net/

Pick an auto company. See how long it takes to get to companies in any other major industry - steel, oil, banks - or even another auto company. Also notice the links to government and universities. And on the latter, note that the database in use here is incomplete - w/ complete data the state/university links would be more extensive.

There are “preferences” at work all over - some of them are consumer preferences, but those are likely the least of the story.


#11

First I have never seen a Smart car billed as a miracle. Not sure what Kool-aid your drinking.

On Sprint’s no one wants tiny cars in the US. A Sprint was a death can due to lack of safety equipment, amenities(AC, Power steering, power equipment) and crash protection structure that adds weight. Lastly 40MPG was easier when cars were not as clean and lacked decent emission control. The challenge is making a compact or larger that gets 40MPG at a reasonable cost.

Good riddance to the Sprint and Geo Metro.

A new entry worth of consideration is the coming 2008 VW Jetta TDI that is going to be certified for emmisions in 50 states. Its mileage will be around 45MPG with mid 8 sec acceleration and incredible power(torque) in traffic all bundled in a very nice mid size car.


#12

[i]

First I have never seen a Smart car billed as a miracle. Not sure what Kool-aid your drinking.[/i]

I imagine the reference is figurative not literal. Look at the “green” marketing by auto companies these days - completely unremarkable forms of change are billed as hard won “progress” in the “fight” to overcome technological hurdles to bring us - the now admiring public - the best that modern technology can offer. And, like marketing tends to be, its a bunch of hogwash.


#13

It isn’t.

This is rocket science ~ F = (m dot * V)e + (pe - p0) * Ae


#14

You also have to look at weight in respect to building materials. Steel is the material of choice because it is strong and inexpensive to use in manufacturing cars. Newer materials, carbon fiber and composites would make a lighter car equal to or greater in strength to steel. The problem is cost of manufaturing is much higher than steel. The tools, dyes and molds needed would also be a huge capital expense. I believe this technology will eventually be used to build cars but not until the cost of these new technologies comes down and the big car companies decide to invest in this new technology.


#15

LOL, real rocket science. (-;


#16

Couldn’t resist it.


#17

A modern Toyota Yaris 5-speed manual transmission car will get 40+ mpg if you drive it as slowly as a Geo Metro will go, in spite of what the EPA sticker states.
My worst tank ever was a 70 mph highway trip against a brutal headwind, got 36.1 mpg. The Geo I owned could also be driven down to the upper 30’s mpg if driven in a similar situation.


#18

The Smart is also not the most aerodynamic car ever designed. It’s an urban golf cart designed to need only half a normal parking space, not a car designed to cut through the air at highway speeds. For that, look at the Honda Insight with its covered wheel wells and boat tail rear end. A coefficient of drag of 0.19 allows it to get over 60 mpg on the highway (but all the credit went to its hybrid power system).


#19

It’s interesting that back in the 1940’s, Nash made a model called the 600. It got its name because it would presumably travel 600 miles on a 20 gallon fill-up of the gas tank. I did know owners who would achieve 25 mpg + with these cars. These cars hauled 6 passengers and weighed about 3000 pounds. The engine was a side valve 6 with 172 cubic inch displacement. The 1949 model had true aerodynamic styling as it was designed with extensive wind tunnel testing.

It would seem that with today’s more efficient overhead camshaft engines we could have achieved 40 miles to the gallon with a full sized automobile. However, people thought that the “Airflyte” styling was ugly. With plentiful, inexpensive gasoline, we moved to the finned monsters of the late 1950’s. We had Buick’s Dynaflow and Chevrolet’s PowerGlide that depended on the torque converter rather than gearing for torque multiplication, and had plenty of slippage. Even after the mid 1970’s when we had a gasoline crunch and small cars became popular, after the crunch we went to SUV’s. Had we made a sustained effort to improve on the Nash design, we might have full size 40 mpg cars.


#20

in england most of our cars will average 40mpg,but most are small cars with 1.3 litre engines,also because of our rediculous petrol prices, (currently the equivalent of $10 a gallon!!),a lot of people are buying turbo diesel.my nephew drives a seat leon,(made by vw)with a high output 2.0 tdi engine,which developes 170 bhp!and will do 130mph!and he averages 45mpg!so maybe turbo diesels are the way forward in the usa?