Cadillac CTS/CTS-V: Real World MPG

mcgreenxmcgreenx Member Posts: 179
First, the reprise of the Check Coolant message, after the dealer sealed the cooling system, seems to have been solved. When the message started reappearing, I noticed the overflow tank had been left open, with cap perched on the cowl. I replaced the cap, the dealer refilled the tank with DexCool, and the message hasn't reappeared in over a week.

Second, after the earlier discussion here on octane, I drove from Chicago to Toronto and back over the weekend, about 1200 miles. Used 93 octane going (which I had been using exclusively) and 87 returning. I always drive until the Low Fuel message, then invariably put in 16 gallons (the tank holds 17.5 per the manual), so by the second tank I think the residual 93 octane was negligible.

There were absolutely no differences in driving perceptions, highway, city or expressway, from one octane to the other. However, I did experience what I consider a very strange mileage phenomenon.

Keeping track of fuel consumption was really weird, because as soon as I crossed into Canada, I had to start using litres and kilometers (it's the law there, and you have to do it in French under risk of being arreted). Very confusing, especially when you multiply the metric hours by Canadian dollars and then convert everything to Celsius. Thank heavens the CTS has a computer to manage all these factors.

Anyway, driving east with 93 octane I got 24.0 mpg. Returning with 87 octane I got.....are you ready?.....26.4!!!! Both segments were essentially identical, highway speeds about 80 mph, negligible wind, comparable weather and the same terrain, and both cities are close to 600 feet above sea level, so it wasn't uphill one way and down the other. Temperature going hovered about 32F and returning was about 38F. I can't explain the difference, particularly the better mileage on lower octane fuel, unless the car just happened to "loosen up and break in" while on the trip (I have about 8K miles now).

In any event, I am going to use 87 octane from now on, unless something happens to change my mind.


  • richw5richw5 Member Posts: 152
    Very interesting!

    Do you know if Canada requires a mix of ethanol (or MTBE) in their gasoline? Our gasoline supply currently contains up to 10% of those additives. I experienced a reduction of about 1 to 2 miles per gallon when the government mandated a "clean air" gasoline mix in the early '90's. Your results may be due to that difference.

    Our gas mileage is always better on a return trip from central or southern Illinois, when we go to visit my wife's relatives. I forget how many gasoline blends the government mandates, but the largest metropolitan areas get gasoline with the least amount of "energy" due to gasoline blend. Therefore they get less miles/kilometers per gallon/liter .

    I think clean air is important, especially for kids, so I don't mind getting a few less mpg.

    Anyway, your experiment has given me a reason to try 87 or 89 octane with our CTS, just to see if it makes a difference.


  • trichard2trichard2 Member Posts: 20
    rsteph, my CTS turned 18k miles,including a 5K mile RT between Phoenix & Detroit. I have used 87 octane exclusively without any engine issues, knock, ping or preformance. The computer indcates 23+ avg. mpg. While I don't drive "at the limits" neither am I real conservative. I have NEVER been embarrassed by this cars performance,
    on the Interstate or in town. I have used the xmission "Sport" mode on occasion and it does step things up a bit.
  • missouri2missouri2 Member Posts: 41
    just got back from the southwest. drove 5000 miles and loved every minute of it. the cts averaged 27.6 mpg for the trip. did a lot of driving around 85 mph. only saw 7 other cts's and one that made me cry it had a vinyl roof. longest i drove in one day was 810 miles and i wanted to keep going. the car is very comfortable and handles great. only complaint it that the front of the hood and windshield chips real easy.
  • wwhite2wwhite2 Member Posts: 535
    I usually have an average mpg between 23.5 and 24 with my 03 5spd manual
  • mannytrannymannytranny Member Posts: 175
    I usually get about 20.5 mpg in the city. Highway mixed driving I get about 26 mpg. I use 93 octane, sometime 91. The worst mileage I got was with 89 octane, 18 mpg in the city.
       I probably could get better mileage if I didn't 'get on it' so often.
  • richw5richw5 Member Posts: 152
    My wife and I just completed a 925 mile trip from the Chicago area to Mackinaw City, Michigan and back.

    The CTS handled superbly. It's definitely made for the road. We averaged 25.5 MPG, which wasn't bad considering we used the AC on the entire trip and ran into heavy rain on the trip up and on the trip back. We also had some major traffic jams back in the Chicago area.

    Unfortunately, I had a problem with water under the drivers seat and on the rear floor. I ran a search on this discussion and located some earlier complaints along with the number of the service bulletin (TSB). The CTS is scheduled to go to the dealer on Monday.

    Now that I've learned how to position my seat, I didn't have any problems with my right leg getting sore. Although neither one of us misses a lumbar support in our CTS, Cadillac should have provided one in the '03's, because when it comes to seating, "one size does not fit all".

    As for brakes, the performance pads on our LuxSport are the best brakes I've ever had. The CTS stops quickly and in a straight line every time.

  • richw5richw5 Member Posts: 152
    We just finished our second 650 mile trip to and from Southern Illinois this month. Since the steering wheel is adjustable and I tilt the seat back somewhat, there is no problem with placement of my hands.

    I averaged 25.3 MPG on the trip, driving into a strong head wind on the leg going south. The CTS is great road car and is solid as a rock at highway speeds.
  • panzerpanzer Member Posts: 125
    I drove our 05 CTS in the snow last week. We had about 6 inches and the roads were icy and snowpacked. I put on Dunlop Sport M3 Winter tires this fall. The car has Stabilitrak. What fun! Between traction control and the Stabilitrak, there's alot going on to help. The car was impressive. Nothing like my Touareg, but not bad for RWD.

    Comments on the previous post. A CTS is a good alternative to a BMW and no I-Drive; way cheaper than a 5-series and cheaper than most 3-series. We also try to buy GM if we are buying American, and the CTS is the hands-down best car they offer. Wouldn't take a Ford or Mopar on a bet. I doubt you'll see 25 mpg except on a nice level highway run below about 70 mph. Ours averages 19.8 mpg in almost 7000 mi of mostly suburban driving. That's the same as the 99 Olds Intrigue that it replaces, and way more fun. The car will go back to the dealer the first time for its first oil change, projected at about 10000 miles. In almost two years, my VW has visited the dealer no less than 15 times. I like both cars very much, though.
  • richw5richw5 Member Posts: 152
    Thanks for the tip on the Dunlop's. The only problem I have with the Goodyears on our CTS is traction on icy/wet snow, going uphill.

    We've got over 43K miles and my wife is getting about 22- 23 mpg on her (part expressway/part suburban) drive to and from work. At first, our mileage was not too good. When we got around 10K miles, it improved drastically. We get about 26-27 mpg on the highway, on a non-windy day, at 70 to 75 mph. Headwinds reduce the mileage to about 20-21 mpg.

    Before my wife started her current job (December) she was getting 18-20 mpg in city/suburban driving. We're both really pleased and my wife uses premium gas, with midgrade at every other fillup.

    As I said before, based on this '03 CTS, our next car will be a another CTS.
  • blckthreeblckthree Member Posts: 153
    Snow is the least of my problems, we don't get much very often. Occasionally some freezing rain and ice, which not much of anything will do very well in. As of right now, I would settle for some rain, nothing that amounts to anything since Halloween.

    As far as mileage, this first tank of mixed driving, about 60/40 highway/city, the DIC shows 21.7 as of right now. That isn't bad for a car not even close to broke in. My daily drive takes me 25 miles across the interstate at about 65-70mph depending on traffic. I think 25mpg is a reasonable estimate, and a huge improvement over the 17mpg of the Yukon.

    I am a little surprised that a head wind has that big of an effect on the CTS. I thought the aerodynamics of it would make for less of an impact on mileage. It killed the Yukon, but it is about as aerodynamic as a brick! Give that Yukon a good tail wind and it could get 25mpg easily.

    250 miles and loving it more each time I drive it!

    Mike :)
  • no1listensno1listens Member Posts: 3
    I have an 2007 2.8 and the gas mileage is a joke. Around town I get about 12MPG and on the highway I get about 20. My roomates Range Rover Supercharged gets 11.7. I brought the car in for service after a couple days of owning it because the engine light was on. They replaced a barometer sensor and ever since then the mileage as been a joke. Not very happy with this car.
  • eebakken1eebakken1 Member Posts: 1
    I'm glad to see that the CTS does well on the snow. My fiancee and I are shopping for a new car and we've found a pearl colored 2003 CTS for 12,000. It appears to be in excellent condition and I would love to have it. My only concern was snow because when I come home from college during the winter, my house gets quite a bit of snow at times and I would hate to wreck my pretty new car.
  • jazzmon1951jazzmon1951 Member Posts: 9
    my 03 cts has gotten 20 mpg in town and 27.5 on highway since day one. currently has 65k on odometer.
  • vtudevtude Member Posts: 1
    i have a 06 cts-v. I have 50K miles on the car. and averaged 20mpg. and i've never reset the reading. i drive in everyday nyc traffic and take regular road trips including a cross country. i use 93 octane.
  • 150mphclub150mphclub Member Posts: 316
    Filled my tank for the first time today at 171 on the odometer (about 50/50 city/highway), because there was a nearby station at $3.84. It took 7.8 gallons.
  • 150mphclub150mphclub Member Posts: 316
    I just filled up after a 425 mile trip (about 85% highway & 15% city). It took 14.95 gallons (about 28.4 mpg)
  • 150mphclub150mphclub Member Posts: 316
    I just drove from Vail, CO to Indianapolis with the cruise set at 77/78 for most of the trip. I got 27.1 mpg.
  • tdbmdtdbmd Member Posts: 20
    Just got a 2010 CTS sedan with the 3.6 and AWD. First tank was 23.6 mpg in mixed driving (70% hwy-30% city) but with straight hwy the average is around 26-27 mpg. Over the exact same commute my '05 LeSabre with the 3.8 liter averaged about 27.5 mpg, so not too much worse for 100 additional HP and AWD!
  • tdbmdtdbmd Member Posts: 20
    In three additional tanks, the mileage continues to be between 22.8 and 23.8 mpg, calculated by hand for my CTS. I have not had a long highway trip yet. This is with using 87 octane, non-ethanol fuel only.
  • paopao Member Posts: 1,867
    09 here as well with none DI engine....had it since Oct 08...approx 38K on it....Im averageing 24 in town...and have hit as high as 31 on the hwy on extended trips.....very happy with the MPG
  • datagendatagen Member Posts: 107
    Is there anyone who has a CTS sedan or coupe with the new V6 that is suppose to be 20-30lbs lighter and pumping out 318 horses? I am wondering what is your current mileage and fuel economy.
  • tdbmdtdbmd Member Posts: 20
    I have noticed that wind will affect the mileage pretty significantly, but that speed does not seem to as much as my old car. Meaning, I get about the same 26-27 on the highway on a calm day at 60 or at 70 mph. At least so far.
  • tdbmdtdbmd Member Posts: 20
    Now a few more months into owning the '10 CTS AWD. Mileage on my commute is pretty steady at 22-23 mpg. I did notice that it went up about 1 mpg when I used non ethanol fuel (not premium, just 87 octane). I have had a few 100 mile trips, and the highway mileage has not been below 25 mpg.
  • wally60wally60 Member Posts: 1
    On my 2013 CTS 3.0 engine just came back from 2400 mile trip on interstate average 26 to 29 mpg running the speed limit with cruse control with 1800 miles on it when i left mpg figure old fashion way very happy with mileage
  • warren_reachwarren_reach Member Posts: 3
    Just drove my 2009 CTS-V Automatic (Magnaflow Exhaust, Cold Air Intake) across the country, about 2,800 miles, averaged 18MPG, mostly 19-20MPG on highway going 80-85mph. Started off with 93 octane on the east coast, only saw 91 available after that. Absolutely terrible power loss at 7-8k feet altitude through parts of Wyoming.
  • Steve EliasSteve Elias Member Posts: 2,207
    thanks Warren - I hope you enjoyed that trip, I will try to make a similar one this year and really enjoyed previous cross-country drives on I-10, I-40, I-90, I-80.

    i noticed huge power loss with my Z28s cross country at altitude, of course. 28 mpg tank after tank with the iroc-z & 87 octane. Huge power loss with the honda civic, mpg was barely better than 30, iirc. VW passat diesel did not suffer much power/torque loss at altitude, apparently thanks to turbo and diesel torque... passat TDI mpg was 35.

    looking forward to someone posting a cross-country mpg reports with the new ~650 hp cts-V ... :) or ATS-V :)
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