Does everybody's gas mileage suffer horribly when you use the A/C? Especially the 420sel. It seems I fill up now twice a week when before it was once a week. I cant calculate my actual mileage because my odo dosent work

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

My daughter told me that she had heard someone say that the AC actually hurts fuel economy less that the additional drag of driving with the windows down. Anybody else ever hear that? How about you engineers out there?

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" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

Tie your daughter to the roof, that's what I do with mine. They get to live their green opinions and I stay cool. It also makes driving the car more peaceful.

I think that is true if you are driving at highway speed.

That's a good one! Actually, she's not one of those obnoxious kids who are always evaluating your every move against something they read in a magazine. Not yet, anyhow.

So, Bot, what do you suppose the drag coefficient of a teenage girl strapped to the roof rack of an SUV is?

__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

Okay, that's good enough for me. I'll keep the AC on then.

__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

I've read that.

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'07 Yukon 2500
'13 Subaru Outback 3.6R
'13 Orbea Carpe 9-speed

Currently Benzless
Formerly: 300TD, S600, E55, 560SEL

---= The forest breathes, listen.
-Native American elder

I keep the A/C off and the sunroof open for as long as possible, but the last few days have changed that policy some. My gas mileage has dropped. I don't know if its the new cat I just put on, or the effect of ethanol in the gas. It has dropped from 18 to 15, even without A/C. ECU duty cycle looks normal too.

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1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma

Yeah, we had it easy for most of June, but the "Washington summer" has come now, full force.

__________________
" We have nothing to fear but the main stream media itself . . . ."- Adapted from Franklin D Roosevelt for the 21st century

OBK #55

1998 Lincoln Continental - Sold
Max 1984 300TD 285,000 miles - Sold
The Dee8gonator 1987 560SEC 196,000 miles - Sold
Orgasmatron - 2006 CLS500 90,000 miles
2002 C320 Wagon 122,000 miles
2016 AMG GTS 12,000 miles

On "MYTHBUSTERS" - they addressed this very subject...

If I remember correctly, windows down was better than windows up and AC on.

The compressor drag uses more energy, thus increasing the fuel useage...

The other situation that could be contributing to reduced mileage may be related to the fuel's reduced volitility during warmer weather and any additional ethanol in the fuel...-

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M. G. Burg
'10 - Dakota SXT - Daily Ride / ≈ 172.5K
.'76 - 450SLC - 107.024.12 / < .89.20 K
..'77 - 280E - 123.033.12 / > 128.20 K
...'67 - El Camino - 283ci / > 207.00 K
....'75 - Yamaha - 650XS / < 21.00 K
.....'87 - G20 Sportvan / > 206.00 K
......'85 - 4WINNS 160 I.O. / 140hp
.......'74 - Honda CT70 / Real 125
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“I didn’t really say everything I said.”
. . . . . . . . . . . . . . . . . . ~ Yogi Berra ~

In one of my MB manuals, as I recall, they list the hp draw at max engine speed for the 150 cc compressor at 10 hp and the 173 cc compressor at 15 hp or thereabouts. Also, as I recall, the 126 bodies came in with a Cd of 0.39, which was supposed to be great for a car like that at the time.