I know, I know... something "car people" aren't supposed to worry about, but I'm curious...

social/environmental conscience thing... :-p

I figured between FSI, slight weight reduction (??? - I think we're talking one belt size, not like the subway sammiches guy...), perhaps slightly different gearing, and better aero dynamics/less drag (???)... the S5 might be a little bit less of a piggy than is the S4?

<ul><li><a href="http://www.fueleconomy.gov/feg/calculatorSelectYear.jsp">http://www.fueleconomy.gov/feg/calculatorSelectYear.jsp</a</li></ul>

Of course, I might be slightly more heavy-footed than I should be...

...8.7l/100km, which works out to about 27 mpg. I am assuming that is hwy mpg, but don't know for a fact.

While that's not bad (and I wonder if that is based on the new testing requirements???), in comparison the 3.0 twin-turbo of the 335i is rated at 300hp, 300lb/ft (which apparently is a very conservative hp/trq rating)and gets 29mpg hwy - again, by the old measuring system.

The relatively fuel inefficiency of the Audi V6's and V8's is one of the reasons I love my little 1.8T so much! Even with Stage II mods I get ~ 30-31 mpg on the highway. That's been very nice.

P.S. I consider myself a "car person" and mileage very much matters to me! :-)

Cheers,

better fuel efficiency... I agree about small and relatively efficient but still very high output turbo-charged engines!

With the MPG drop under the new system the A6 4.2 will be tagged with a $1000 tax. (It already has the 4.2 FSI)

The S4 Manual will bump up to a $2600 tax...reason enough for Audi to get the FSI 4.2 in the S4 ASAP.

Vehicle City HW Combined Tax
A6 18 25 24.2 $-
S4 Auto 15 23 20.9 $1,300
S4 Man 15 21 20.3 $1,700
New EPA A6 16 23 21.8 $1,000
New EPA S4 Auto 14 21 19.4 $2,100
New EPA S4 Man 13 20 18.1 $2,600

For comparison, the 3.2 in B7 A4 is newly rated at 25 highway.<ul><li><a href="http://www.fueleconomy.gov/feg/calculatorCompareSideBySide.jsp?column=1&amp;id=23493">http://www.fueleconomy.gov/feg/calculatorCompareSideBySide.jsp?column=1&amp;id=23493</a</li></ul>

Also, shouldn't the 6spd transmission help with fuel efficiency vs. the automatic in the A6?

under the new system the 335i manual will drop to 26 mpg highway whereas a 3.2 A4 quattro manual will be 25 mpg. I know the 335 has a nearly 50hp advantage over the 3.2 and still gets 1mpg better HW mileage, but conversely the A4 has AWD. Which for BMW will likely equal a 2mpg HW penalty based on comparison between 328i and 328xi.

So we are likely to see a 335xi with 300HP getting 24mpg HW vs. an A5 3.2 with 265HP getting 25mpg.

wishful thinking!

So the fuel effeciency benefits of manual transmissons has disappeared compared with maybe 10 years ago.

As for the weight aspect... an A6 4.2 curb weight is 4222 lbs. The S4 Auto is 3946 lbs. and the S4 manual is 3869 lbs. I place my bet on the S5 weighing somewhere inbetween, but perhaps closer to the S4. Maybe a 6sp S5 weighing in at an automatic S4's weight. There is approximately a 1-2% increase in fuel economy per 100lbs lost. So even if the S5 weighs in at 300lbs lighter than an A6 4.2 it should only theoretically get about 5% better gas mileage so may 17 city 24 highway if they kept the exact same gearing as the A6 which they won't. BTW 17/24 is just about the minimum to avoid the GG tax.

And that is good information to know. That would lead me to believe the 3.2 is relatively efficient with the difference in mileage to the BMW coming from weight and/or quattro.

The current manual S4 is rated @ 13.3 liters per 100 km in the European test (RS4=13.4) The tiptronic S4 is rated @ 12.3 liters per 100km. The S5 manual is rated @ 12.4 liter per 100 km.

But the real downer is that the A6/A8 with the 4.2 FSI and 350 hp are rated @ 10.8-.9 liter per 100 km. Or significantly less. I think that the S5 with the 7 speed DSG (it there is one) would get an even better rating than the A6/8.

Also, the 3.2 FSI multitronic A5 is rated @ 8.7 liters, which is much better than the 9.5 liters that the current A4 3.2 FSI is rated at.

*Euroepan fuel economy ratings are for combined fuel economy. But they don't always 100% translate to EPA combined fuel economy ratings. The A6 4.2 FSI gets a 21.8 European fuel economy ratings but only 20 EPA combined rating. Plus the new EPA test is a wild card with no data to see the new relationship.

P.S. I don't think that the new standard will be applied to the gas guzzler tax. The gas guzzler tax is also a joke as it is currently. It doesn't apply to SUVs/pickups. Each year there are 8 million SUVs/pickups sold that don't pay the gas guzzler tax but should [according to the EPA table in the link] But, cars lke the S4 do pay the gas guzzler tax, I am sure that there are only about 50,000 vehicles or so sold each year that do pay the gas guzzler tax.<ul><li><a href="http://www.fueleconomy.gov/feg/info.shtml#guzzler">EPA Gas Guzzler Table: Read text above table as well</a></li></ul>

Does anybody have a quick cconversion factor for L/100km to MPG? I know I should know it, but I don't... sad, sad.

But with the new EPA ratings we will have to wait and see how closely the European and EPA ratings are related.