http://www.fueleconomy.gov/feg/tech_adv.shtml
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It has all technology that is currently available, and economical/commercially viable, to increase fuel economy. Some are widespread as well as more mature, like VVT. Others are new, yet relatively simple (AMTs). Combined, they can increases fuel ecconomy 40-55%. This may result in >2ton SUVs/light trucks with combined fuel economies in the 20-25mpg range. Not great, but better than 14-18mpg.
_With B-D cars, and other 1-2 ton vehicles, the benefits could be uneven, due to the fact that many of these elements are already included in current models. However, a jump of ~1/3 could be expected. That is not bad, with D cars jumping to the upper 30's, and Cs in the upper 40s low 50's combined. This is without a full hybrid system.
_It comes down to cost. With all the equipment, it could get expensive, even up into the price range of full hybrids and clean diesels. If fuel prices stay high, all this may be rolled out and combined into an automobile quickly. Think of it as an alternative to low end versions of clean diesels and hybrids.

Allen Z -

if only it were as simple as deploying VVT and AMTs. The combination of these two - or indeed any two - fuel economy measures will not by itself yield vehicle fuel economy improvements anywhere near as large as you indicate. Try 7-10% in standardized (and unrepresentative) test cycles, if that. Btw, AMTs are no more efficient than those AT designs that feature bypass clutches for all gears (e.g. Mercedes).

Moreover, the continuing trend toward ever-larger, ever-heavier vehicles anyhow pretty much nullifies any gains made in the drivetrain. Concepts such as the Prius are sadly exceptions that prove the rule.

High oil prices did dissuade SUV purchases for a while but they are now back with a vengeance. Therefore, it does make sense to shoot even for a 2MPG improvement in a class that gets well below 20MPG today.

In addition to winning the SUV Grand Prize with the Jeep Grand Cherokee, Dr. Z boasts the feel-good flexfuel (smaller) 4.7l engine which gets EPA 10/13 rating on ethanol. Kids, who is the eco-poseur hiding behind that mustache?

Taxes. We need to gradually raise the price of gasoline. Mileage will improve. Forget CAFE.

Bentley Azure - Subcompact Car??

Hybrids are in 3 car classes out of 12, and it looks like a few more groups will be getting hybridized like the passenger van category. Sweet.

Mike

Nick is correct you need high gas prices nobody is going to buy a hybrid (except for the people who post here) if gas stays low. Watch the SUV sales soar

There's no guarantee that these gas tax revenues would fund alt fuels; they'd more likely go to ambitious politicians' pork barrel projects...or just into their pockets.

I'm impressed that Ford actually has vehicles with good ratings in fuel economy. They should work on the rest of their lineup to match the MPG of the Japanese competitors.

I was not refrering to any combination of 2 technologies listed. I was refering to combining 5-6 out of 7 of listed equipment that would increase performance/save fuel.
4 or 5 of:
VVT, DOD, Turbo/supercharger, DI, ISG.
and
1 of 2:
CVT, AMT.
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http://www.fueleconomy.gov/feg/tech_adv.shtml
http://www.fueleconomy.gov/feg/tech_engine_more.shtml
http://www.fueleconomy.gov/feg/tech_transmission.shtml
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Sites contain links to various other resources, some not working.

VW TDIs get great mileage. I presume the only reason that they are not listed is because VW has skipped the 2007 model year, retooling to meet diesel emissions standards.

VW TDIs don't cut it as a "Green Car". The particulates emitted by those things are orders of magnitude more harmful than the CO2 they are emitting less of. Maybe the situation will improve with the new standards

Allen:
I tend to agree with Rafael on fuel efficiency potential of combination of technologies you listed (with exception of lean gasoline DI with NOx absorber – this technology could bring 20+% improvement alone).

Also couple of forgotten technologies, which could markedly increase highway mileage:
Improvements to undercarriage aerodynamics, variable geometry cooling air intake, reduced height for small cars.

Mark RW Jr -

you have a point. In e.g. Germany, fuel taxes represent the second largest source of revenue for the finance ministry. This creates it aperverse incentive to favor increases fuel consumption.

For the US, one option would be to refund 100% of fuel tax revenue as income tax credits (x2 if filing jointly). This redistributes wealth from those driving gas guzzlers to those driving frugal vehicles or using alternate modes of transport, bypassing Congress. It may be sensible to reserve a fraction for special incentive programmes to encourage technology adoption, especially by those who could otherwise not afford the higher up-front cost.

Andrey -

Audi tried stratified GDI + NOx aftertreatment in Europe but it proved too expensive in spite of the fuel savings. You can get about 80% the benefit with homogenous GDI plus VVT (cam phasers + discrete lift steps) plus thermal management, at a much lower price. More is possible if you provide a long top gear and Atkinson detuning for freeway driving under cruise control.

The aerodynamic improvements you point out would become relevant at high freeway speeds. For fuel economy in stop-and-go traffic, nothing beats reducing vehicle weight. Recuperative braking into ultracaps comes close but it's too expensive.

Rafael:
Everything new is expensive. High development cost and desire to profit from technical sophistication drive initial price of new tech higher that it will be after couple of years in production.

GDI engines for Audi, VW, and Mitsubishi are widely sold in US/Canada for more then a year. Price premium is not so substantial for these marvelous engines with high output, high compression and VVT, and up to 10% better fuel efficiency then comparable traditional engines. However, they are tuned to work on overall stoichiometric mixture to allow proper function of 3-way cat. According to Japanese publications (probably overoptimistic), GDI working at lean mode delivers up to 30% gain in fuel efficiency – “approaching comparable diesel”. The difference is that even with late intake valve closure providing mild Atkinson/Miller cycle, at partial load stoichiometric engine still requires substantial throttling with all associated losses. The problem, as I understand, is that NOx absorber cats are not yet up to the job, but this situation changes rapidly. About month ago I bought regular replacement cat for my vehicle (universal fit, EPA approved manufacturer) for 110$ US with delivery. I do not expect NOx absorber cat will cost much more in mass production.

Regenerative braking and engine shut-off and instant restart for stop-and-go city driving are genuine feature of hybrids, and arguably are not prohibitory expensive, especially in mild hybrid like Honda Civic and micro-hybrid like Saturn VUE. Supercaps can not supply enough energy for vehicle electrical system operation and especially air conditioning during vehicle stops, so batteries are preferable for such applications.

Aerodynamic drug accounts for more then a half of energy required for highway cruising. Especially in Europe, with higher highway speeds. It is very important to keep it as low as possible. Same with vehicle weight for stop-and-go traffic.

The offerings for 2007 are lousy. We know that European <=2 liter turbo-diesels are producing as little as ~120-140g/km results with quite usable and pleasant interiors. Our near-term energy solution is simply to modify and manufacture these cars in north America. It's not right to give away subsidies to purchasers of hybrids just because they're trendy. The way we're going to see significant improvements in our transportation sector is to offer affordable, good looking, functional, HIGH HIP-POINT vehicles that ordinary people can afford. The sub-3000lb. European diesel, combined with SCR and particulate trap, combined with stop/start, and yes - the option of a micro-hybrid, will revolutionize the domestic scene. These can be profitably sold for transaction prices under $20K. The feds can help by reserving a big spot on the Mulroney sticker for a 150K mile fuel cost at $3/gal. This way, shoppers can simply add the fuel cost to the sticker price, and get a comparable figure with which to judge their purchase. The savings of around $5000 will hopefully convince a large number of consumers to go green.

Shouldn't these rankings be adjusted using the estimated average based upon the combined rating?

JC- That is one of the best suggestions right there: A spot on the sticker for the 150K mile fuel costs at $3/gal. Gas prices may fluctuate but each year it could be updated to show a close to national average price (even if it is 25 cents higher or lower than the local gas prices it is still a useful number to me). They could tack it on right next to the EPA gas mileage numbers.

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