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MPG when switching from 3.6L V6 to 2.4L I4?


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Saturn recently released a I4 variant of the Saturn Vue XR. The 2.4L VVT DOHC I4 is more or less a 4 cylinder engine from the same family and with similar technology to the 3.6L V6 offered in the Vue. The I4 comes with a 4 speed auto versus the 6 speed auto in the V6 however. The I4 was previously available in the base model, but the new release is that the upscale XR can also be fitted with a 4 cylinder.

The 3.6L V6 in the Vue is similar to the base, non-DI 3.6L V6 in the CTS.

The I4 Vue is EPA rates at 19 mph city and 26 mph highway. The 3.6L Vue is EPA rated at 17 mpg city and 24 mph highway.

From this comparison one might conclude that the 169hp 2.4L I4 (Vue) is worth 2 mpg in the same vehicle as compared to the 257hp (Vue) 3.6L V6.

Hard to tell exactly because of the different transmissions used also. For 2mpg vs 100hp I'll keep my 3.6L thank you very much.

There is a turbo 2L I4 as used in the Saturn Sky Redline and Pontiac Solstice GXP. That configuration actually gets BETTER gas mileage in the Sky/Solstice (auto 19/27 mpg) than the 2.4L nonturbo I4 (auto 19/24 mpg). The Turbo 2L I4 makes 260hp and is the 4-cylinder I would want to see offered by Cadillac.

Bruce

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On the current methodology, the best DTS is rated 15/23 mpg (performance sedan 15/22 mpg).

The best Northstar V8 is the V8 STS RWD at 15/24 mpg.

The base model CTS non-DI 3.6L is the current US-Cadillac mileage leader at 18/26 mpg.

Worse is the non-HYBRID Escalade at 12/19 mpg.

Bruce

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On the current methodology, the best DTS is rated 15/23 mpg (performance sedan 15/22 mpg).

The best Northstar V8 is the V8 STS RWD at 15/24 mpg.

Using MY current methodology, which is AKA actual driving, I can pull 28.5 avg. mpg for 106 miles starting at St. Clairsville OH and ending in Marietta, OH.

This may be ideal conditions, since the route, though not exactly flat is fairly so. I set my cruise at 71 mph to do this, which seems to work just fine for both of us. The only time I take it off of cruise is on the entrance/exit ramps, which do require a little bit of a gentle application of the throttle.

I'm sure any of the above mentioned engine/trans combinations can do better than this though. All I can tell you is that the ratings don't always tell the whole story.

BTW, I'd swear that my '08 DTS was rated 26 highway, are there new 2009 rating numbers?

Never underestimate the amount of a persons greed.

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Well, I just followed the link to the new 2009 mileage figures............NICE! This will NOT sell a LOT of Cadillacs, and seems to be very unrealistic. Surely the current line of engines hasn't lost that much economy. I'm sure this will make many buyers of these cars very happy when they get better than stated actual fuel economy.

If I were to surmize ONE THING from this comic book of numbers.....It sure makes E85 look good! (which is the intent of this biased rating system)

Never underestimate the amount of a persons greed.

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On the current methodology, the best DTS is rated 15/23 mpg (performance sedan 15/22 mpg).

I am with JohnnyG,

I have driven several DTS's in the last three years... including putting about 85,000 miles on the two that I have owned.

On NON performance ones, I could always get 25mpg or a hair better. And that is driving on the highway around 80/85.

My Performance Sedan gets 21/22 at 80/90mph.

I know that BOTH TYPES of DTS would get better mileage if I slowed down a bit. :D:D

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They might get better mileage at 80, but the tests are run using a particular methodology in an attempt to accurately predict the mileage most people will experience.

The methodology is changed now and then in order to be more accurate. When it is, the previous and new mpg ratings are shown. The window sticker for the FWD Northstars was previously higher; under the new method it is lower.

My 4.9L 200hp 92 STS tended to get 24-25 mpg; my 96 STS w/4.6L got around 22-23mpg; my 05 3.6L CTS gets 26-27mpg by comparison.

Bruce

2023 Cadillac CT4-V Blackwing

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They might get better mileage at 80, but the tests are run using a particular methodology in an attempt to accurately predict the mileage most people will experience.

The methodology is changed now and then in order to be more accurate. When it is, the previous and new mpg ratings are shown. The window sticker for the FWD Northstars was previously higher; under the new method it is lower.

My 4.9L 200hp 92 STS tended to get 24-25 mpg; my 96 STS w/4.6L got around 22-23mpg; my 05 3.6L CTS gets 26-27mpg by comparison.

I'm sorry... I wasn't clearer in the other post....

I didn't mean that they got BETTER mileage at 80... I meant that is the way I drive. :D

JohnnyG gets better mileage than I do. He drives a little slower also.

A couple of weeks ago, I had a DTS LUXll for a few days. One tank of fuel gave me a little over 26mpg... I wasn't in a hurry that day. :D The other tanks gave my 24 to 25.

I am sure that the DTS, driven a little slower than I usually drive... will give consistent REAL WORLD, all highway, mileage figures of 25+. Or at least that has been my experience with them so far.

But, of course, the methodology they use may not be ALL HIGHWAY. I don't know.

But as to the original statement... about 2 mpg or an extra 100 hp...I will take the HP anyday over a tiny 2 mpg gain. :D:D

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I agree. Give me a high tech engine that makes the same hp for better mpg, then ok. Offer me econo-car performance with slightly better mpg and no thanks.

Bruce

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The point of all of this seems to be pretty evident to me. Don't buy a highway car and try to go grocery shopping with it....period.

The METHODOLOGY might try to duplicate actual "real world" driving activities, but in the end it's just a government concoted formula. This means that any INTELLIGENCE whatsoever is automatically subtracted from the equation.

When I need to purchase a grocery getter, the new GM VOLT is tops on my list. "0" mpg is what I'll be after! Second on my list will be a Prius. Face it, these cars do exactly what they are designed to do, just like Jim's car, and my car do.

Believe me, there have already been more than a few times that I wished I had the lower gear ratios. Like the DA in the 300 throwing beer cans out the window while passing and falling back behind the new DTS! Yes this is acceptable behavior in parts of OH. The '99 would have given him a new perspective of power I'm sure.

Come to think of it, has the EPA come up with a new methodology that fairly compares MPG ratings for the Volt yet?

Never underestimate the amount of a persons greed.

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The METHODOLOGY might try to duplicate actual "real world" driving activities, but in the end it's just a government concocted formula. This means that any INTELLIGENCE whatsoever is automatically subtracted from the equation.

Now... THATS a statement I can wholeheartedly agree with. :D

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