I wanted to repeat and save this post for posterity.
Posture, or posteriure.

This thread has again been watered down.

Brother-in-law restored an older VW Rabbit. I believe it's in the 40's too

Checked my 2008 Golf GT Sport this morning - thing is fitted with a 2.0 litre diesel 170hp - goes like stink and is averaging 60mpg.
Diesels are pretty good over here.

The biggest inefficiency in and internal combustion engine is heat.
About twice the HP of the engine is wasted in heat... So if you had a 100hp car 200hp is lost in heat.
Have you ever seen an exhaust manifold glowing red hot?

If you could capture and use that heat it would make a huge difference in economy.

This. And the power draw to run the larger electrical systems. Deduct an additional however many MPG because we have crappy ethanol gas now too.

60mpg! I've heard nothing but good things about those turbo diesels.

This. Frankly it's baffling to me that we don't have more diesels. Excellent MPG without compromising performance. I always hear the line "Americans won't buy diesels", but then I also hear that it's difficult to find a VW TDi or some of the MB diesels because they're popular. There's really no need for all of the hybrid high-tech complexity, just get a car with the 100 year old engine technology for as good/better MPG.

I'm looking for a used compact truck 4x4 that will get decent MPG, in my mind the only truck worth considering is a Toyota Tacoma. With a 4-cylinder and a 5-speed it's a 24-ish MPG truck, and gutless as hell. Elsewhere you can pick up a diesel HiLux (Tacoma) 4x4, crew cab, diesel that will get 30+ MPG all day long and tow similar to a 1/2 ton. How can anyone claim that 30+ MPG trucks wouldn't sell here? Or 30 MPG full size SUVs?

We need a fluorescent or LED motor not that incandescent stuff.;)

You canna change the laws of physics!

Red nailed it (again). The schit that comes out of the fuel pump (that used to be called "gasoline" way back when...) delivers FAR lower potential BTU/h per unit than the old fashioned gasoline used to. That's a big factor. Another is the fact that today's cars are heavy as heck - they're loaded down with all kinds of mandated emissions and safety crap that probably adds 500 pounds or more versus vehicles from years ago - and that's despite advances in body panel composition, etc. which are lighter.

The EPA mandates for diesels kill the mileage and make it hard for manufacters. The Ford 6.4L is a great example. When you remove the DPF and retune it not to regen, the mileage increases by 3 -6 MPG. I would love to have one of the little diesels from Europe as a DD. Quiet, peppy, and great mileage.

That's correct.

In 2004, the U.S. purchased more trucks than cars. 52.7% of ALL vehicles sold were 'light' trucks under 8500# GVWR. The CAFE standard was 20.7mpg. The fleet averaged 21.4mpg. The average truck had 237hp. 2% were diesels.

Just twenty years earlier, in 1984, light trucks represented only 24.4% of the market. The average truck had 119hp. 2% were diesels.

What isn't seen in this data is the tripling of sales in the over 8500# GVWR personal trucks (Excursions, Suburban 2500s, F250/350s, 3/4-1 ton GM and Dodge, etc) between 1984 and 2004.

With ALL light-duty trucks in the mix, we bought 7.1 million trucks last year (2010), versus 5.1 million cars. That's almost 40% more trucks than cars.

Today, if you want to make an impact, you will save more fuel by increasing the truck fleet just 1mpg than you would selling triple the number of Prii, Insights, and Jetta diesels. In 2010, hybrids accounted for only 2.4% of all vehicle sales. Diesels were less than 1% of all vehicles sold (under 8500# GVWR).

Does this math not make sense to you?

An interesting bit of information I remember from high school.

Apparently if you could build a rocket that had 99% efficiency you could use that rocket to launch
the average car into space using just one full tank of gas.

Of course the problem is we can't build any engine that's anywhere near that efficient.

I seriously doubt that. I expect it was not a physics teacher saying that.

I can't remember the teacher that said it but apparently there is that much energy in a tank of gas.

If you think about it we have cars that can travel above 200 mph on an engine that may be 20% efficient at best.
How fast could that car go if the engine was 99% efficient?

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As a side question. How efficient are modern rocket and jet engines?

We need to fund a more powerful diesel lobby.

It is criminal that we get subjected to this ethanol crap while the mileage in our cars goes down and we have to deal with all the ethanol related issues with our car and small engines.

Not to mention the higher price for food and the ripple effects of corn prices on all industry.

Look up the MPG on some of the european diesel cars - eye opening...

They're also rated on VERY different cycles than our own EPA testing. Not apples to apples. Impressive, nonetheless. Just don't expect to bring it here and see the same numbers on the window stickers.

Audi A3 - Saving you fuel - Audi.co.uk

Ours is the 1.6tdi shown here. Doesnt set the world on fire but I got 90mpg on a 50 mile trip coming home yesterday (wife and 3 kids).
I have never seen less than 50mpg around town.

per U.S. gallon? Or British Imperial gallon?

Thats a British gallon.
I know the US one is smaller. So maybe someone with more brains can recalculate.