Modded CTS-V 27.4 MPG

[YukonCornelius]

Originally Posted by mcrews

Given the right gearing, I think it will become more common for newer cars to get better mpgs w/ 'the adjustment of the nut behind the wheel'
Also you metioned the having the live mpg screen on. That is one of the main reasons for my initial leap into the mpg world.
My Q45 can be a beast but I was always trying to 'beat the screen'!

I wish I had the 6th gear!!!!

I'm the same with the read out, any car that has one I love watching it. Your 5th is probably similar to my 6th.

[mcrews]

1. my rear ratio is 2.78. not sure about my 5th....maybe .7X?

2. The mpg scree in the infiniti is large and easy to see. I use the scangauge now because it is exact.
3. I run 245/50/18 in the factory 18 alloys. 27.7" dia. The factory tire was 245/45/18 at 26" dia. So my car's readings are off.
4. I think I'm at 1800 rpms at 65mph

5. My daughter just got the 2011 Edge Limited. I love all the high tech dash.....except the mpg screen is small.

[bhazard]

Wow are those 6-lug wheels?

[YukonCornelius]

Originally Posted by bhazard

Wow are those 6-lug wheels?

Yep. Kind tough to change wheels with that. But I wouldn't change these out for anything else. I think it had something to do with the stress on the wheel bearings in cornering and the 6 lug set up was the strongest in the parts bin. This thing corners hard. Right now my g-meter is showing 1.15 registered, I did it through a sharp corner I have experience with.

[Domman56]

WOW Jealous You're pushing about the same power outta that as my 04 CLK55 but the best tank i've ever gotten was 25.1 MPG. Love having the V8 power when you want it and good fuel economy when you need it though

[UltArc]

I am looking forward to the Cape Cod results

[gikard]

I'm very impressed. I just bought an 06 and I'm shocked it gets worse mileage than my outgoing BMW 540i even though the EPA says otherwise.

Can you share how you tricked the ECU to go into lean cruise mode?

[cRiPpLe_rOoStEr]

Originally Posted by Domman56

You're pushing about the same power outta that as my 04 CLK55 but the best tank i've ever gotten was 25.1 MPG.

Altough the good old cam-in-block setup of the LS engines is often blamed for being "too old-school", it still can fare decently mileage-wise comparing to modern opponents from European and Japanese automakers.

[gikard]

Yup. The 04-07 CTS-V has comparable power and weight to the 2003 BMW M5 and does get better real-world fuel economy.

Not only that, but

- if you were to put them in a box: the LS2 and LS6 motors actually fit in a smaller box than a DOHC V8 with comparable output power (e.g. 5.0L 2003 BMW M5 motor) due to the width of the latter's cylinder heads

- the LSx's weigh less

- the LSx's have a lower center of gravity


One thing I like about the CTS-V over the 5-series is it uses A-arms in the front suspension, instead of McStruts, which is kinder on the tires in spirited driving ... probably because they can fit with the narrower LSx engine.

The whole hp/L argument is a bit misguided, hp per external dimensions, per weight, and per BSFC @ cruise conditions are probably better metrics.

[pgfpro]

Originally Posted by Lbar

I wanted to post this up since it's not the norm here. I have a 05 CTS-V that has a the Z06 LS6 and 6 speed. I have a larger than stock cam in it .580/.580 220/226 117lsa, full length headers, no cats, f.a.s.t intake manifold, ported 90mm tb ect ect.

Now onto what you guys care about. My current best full tank to date is 27.4 MPG. No engine off coasting or pulsing, not even much drafting trucks (rock chips). The car was loaded with stuff and a passenger doing a highway trip to New York (187 miles) a week of short trips where I was, the whole drive back and then some more driving around. I had all the tires around 50psi. My car has a setting for a live MPG display and from the testing I've done the thing is just about dead on. This isn't my daily so most of my usual driving is short distance and hard on throttle so I haven't made a effort to beat my full tank MPG record.

However, I have made two major ecomodder mods. First, Cadillac didn't use DFCO on this cars tune because a Cadillac is supposed to roll when you let off the throttle. So I have it set that DFCO will now engage in all gears except first at any speed and at any RPM and it doesn't feed fuel again until 1100 RPMs. This was about as low I could go and not have to worry about a possible stall. Next, and this is major, I found a way trick my PCM to accept the lean cruise that GM uses on some Australian cars. Going off my live MPG reader my car seemed to like a 16.3 AFR at cruise. And it gained 2-3 MPG from this when shutting it on and off while driving. I have the settings cranked up though, engaging lean cruise low at 40mph in any gear, and it will hold until I get about 1/3 down on the throttle. In good air by myself and on a flat highway I can cruise getting 41 MPG.

The one fault of this car is the stock gears are 3.73's. Oddly enough with my custom grind cam my car seems to get more efficient with higher RPMS when cruising. Doing 50-55 mph I have trouble getting my live mpg reading to stay at 30. If I bring it up to 72-75 I'm well into the 30's or even low 40's and can feel I'm using much less pedal. I'm going to make at road trip to Cape Cod next month and I'm looking forward getting a new best. I'm confident that I will break 30, 34 would make me really happy. I'm so tempted to block off my whole lower grill and brake vent ducts in the front but I'm a little self conscious about it on this particular car. I'd like to do a couple extra things before I leave though.

Nice set up!!!

I didn't know the Australian cars had a lean burn mode? Very cool! Anyway let us know hot the Cape Cod trip goes.