At Eco-marathon, teen driving team races to 2,843 mpg

[Amianthus]

I don't know which gas company is cutting your check but I just showed simply how the weight shouldn't be an impediment to getting a car that runs 100 miles to the gallon.

You don't need an engineering degree to know how to divide.  If weight is the issue, then it seems the ratio of weight should be relative to the mile per gallon.

You do, however, need to an engineering degree (or at least some study of the principles) to understand that the fuel consumption / weight ratio for internal combustion engines is not a linear ratio, and therefore simple division does not accomplish what you are trying to show.

I can show you light weight cars that have LOWER gas mileage than SUVs. Totally blows your theory out of the water about weight being the only factor.

Oh, and BTW, I'm in the health care industry currently.

[Xavier_Onassis]

Government mandated safety equipment includes safety belts, a two-chamber master cylinder, an airbag or two, some sort of bumper (though nothing like the bumpers they used to make in the 1980's), and a steering wheel that will not impale the driver like a bug.

I don't think these items weigh very much, even though it is always a hoot to blame the government.  I doubt that these things weigh 6% of the total weight of a Miata. One obese passenger would decrease mileage more. What decreases fuel mileage are weight, friction and air resistance. The new cars are all very aerodynamic. An old Volvo or a VW Microbus is like pushing a brick through the air.

Engines are MUCH more powerful than they used to be. My old '81 Buick Regal had a 3.8 liter V-6 and it had about 90 bhp. The same engine block  in newer GM cars gets the same 18-22 mpg or better and puts out over 300 bhp.

I would think that 100 mpg would be about all you could expect from any internal combustion engine, 4-passenger capacity vehicle. Maybe there are fuel cell, hybrid or magical mystical turbines that  could do better. I really hope there are.

For some reason, the Wankel engine, which just whirls around and around and has many fewer moving parts, has always gotten worse mileage than the internal combustion engine with all its many parts travelling in a variety of directions,

I do not know what that reason is, but I am guessing friction has a hand in there.

[Amianthus]

Government mandated safety equipment includes safety belts, a two-chamber master cylinder, an airbag or two, some sort of bumper (though nothing like the bumpers they used to make in the 1980's), and a steering wheel that will not impale the driver like a bug.

You're missing a lot of the changes that are directly attached to the engine in that list. Well, I guess a lot of those are government mandated pollution reduction equipment, not safety equipment, but they are government mandated nonetheless.

[Amianthus]

Engines are MUCH more powerful than they used to be. My old '81 Buick Regal had a 3.8 liter V-6 and it had about 90 bhp. The same engine block  in newer GM cars gets the same 18-22 mpg or better and puts out over 300 bhp.

A lot of the power increase comes from better "breathing" (more, larger valves) and fuel injection. A similar displacement V-8 will have more power still, and might even have a better fuel economy, because the power strokes are balanced.

Matching engine output to the weight of the vehicle will significantly affect mileage as well. A small engine on a big vehicle will get worse fuel economy than an big engine on a small vehicle.

Interestingly enough, removing the thermostat (something people do on older small block V-8s to help the engine run cooler) will also decrease your mileage.

[Brassmask]

You do, however, need to an engineering degree (or at least some study of the principles) to understand that the fuel consumption / weight ratio for internal combustion engines is not a linear ratio, and therefore simple division does not accomplish what you are trying to show.

I can show you light weight cars that have LOWER gas mileage than SUVs. Totally blows your theory out of the water about weight being the only factor.

Ami,
Do you understand that your stance on this is antithetical to the idea that I imagine we all share that cars should get higher gas milage?

It amazes me that your comments seem more intended towards blowing my theory out of the water but it seems more to me that it really just proves my point that something is totally f'ed up when an SUV can get higher milage than a Miata.  That seems to prove to me that someone is dropping the ball somewhere.

It was your assertion that the weight was the problem, so I went from there.

Oh, and BTW, I'm in the health care industry currently.

Doesn't mean that a petroleum company can't be cutting you a check to spread their propaganda.  Or will you now assert that it does somehow preclude you from getting a petroleum-based side pay?

[Amianthus]

It was your assertion that the weight was the problem, so I went from there.

I never said that weight was the only problem, though it is the main one in this case. However, your simplistic linear ratio approach to the issue is hardly supported by the physics of the real world. In the case of these vehicles, your approach of doubling the weight for the winning vehicle with the 2,800+ miles per gallon will not result in a vehicle that achieves 1,400+ miles per gallon. It will probably drop that number considerably, most likely to the range of 100 miles per gallon. And that would only be effectively adding one passenger and a seat. It's also likely that vehicle wouldn't even move if you added that much weight. I saw one of these competitions once - one of the vehicles, though it got good "mileage" out of it's engine, would barely move if a wind picked up blowing in the other direction. These vehicles are designed with very small motors that provide just the bare amount of energy needed to move the vehicle, and very slowly at that. Eat a big lunch, and your car might not be able to take you home, with the slim tolerances on power for these vehicles.

It amazes me that your comments seem more intended towards blowing my theory out of the water but it seems more to me that it really just proves my point that something is totally f'ed up when an SUV can get higher milage than a Miata.  That seems to prove to me that someone is dropping the ball somewhere.

I didn't say a Miata. I said a lighter vehicle. It was not an endorsement of lower gas mileage, however. It was just an example that your simplistic approach to subject is hardly supported by physics in the real world.

Doesn't mean that a petroleum company can't be cutting you a check to spread their propaganda.  Or will you now assert that it does somehow preclude you from getting a petroleum-based side pay?

There are a number of industries that I am forbidden from dealing with due to my current position. I can't even invest as a stockholder in a number of them, much less take money from them.

And stating facts about the physical world is hardly "propaganda."

[Brassmask]

So, Ami, let's flip it.

How do we get vehicles that get 100 mpg?
 

[Amianthus]

So, Ami, let's flip it.

How do we get vehicles that get 100 mpg?

Well, we could get real close TODAY with the removal of some government mandates. There are diesel vehicles sold in Europe RIGHT NOW that get over 80 mpg. They cannot be imported because they do not meet US safety and emissions standards. This is but one example of the hampering effect of government regulations.

Here's an article for you to read up on: http://www.popularmechanics.com/automotive/how_to/3374271.html

Interestingly enough, one of the engineers quotes some numbers about weight and fuel economy - reducing the weight by 10% increases fuel economy by about 7%. So, that shows that the ratio is non-linear. Also, since it's a curve, that particular ratio is only applicable for normal vehicle weight ranges - between a ton and two. Once you're outside that range, the ratio changes dramatically.