Gibby Posted December 15, 2013 Report Share Posted December 15, 2013 This has probably been beaten to death but I wanted insight and opinions. Google says a tgp should average 18 mpg. Mine averages 18-21 mpg. How are some of you getting high 20's and even 30's?? I have no vac leaks, hooked up to a smoke tester to make sure. Crossover is rebuilt. Car runs great... Just can't getthese mpg numbers up to what some of you say is possible. Thanks for input. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted December 15, 2013 Report Share Posted December 15, 2013 http://www.fueleconomy.gov/feg/calculatorCompareSideBySidePopUp.jsp?column=1&id=6781 EPA original ratings of 17/25..... which doesn't seem very different from what i'm told they achieve real-world. Quote Link to comment Share on other sites More sharing options...
virtuetovice Posted December 15, 2013 Report Share Posted December 15, 2013 LIGHT feet. Boosted cars have this magic thing in the pedal that makes you want to press it harder. I can get between 14 MPG and 24 MPG average, but it ALL depends on how you drive. Quote Link to comment Share on other sites More sharing options...
redgrandprix Posted December 15, 2013 Report Share Posted December 15, 2013 it depends on the distance, I've gone on car cruises that are a couple hundred miles and hit close to 30mpg but my regular 30ish mile drives to work and such bring somewhere around low to mid 20's Quote Link to comment Share on other sites More sharing options...
Schurkey Posted December 15, 2013 Report Share Posted December 15, 2013 Decreased mileage in many GM vehicles can be due to piston slap irritating the knock sensor, which then causes the ECM to pull timing. Power and mileage both decrease. I've got a pair of 3.4 twin-cam Luminas with this syndrome. Of course, the knocking noise is the major clue, here. Confirmed with a scan tool to check knock sensor activity. Quote Link to comment Share on other sites More sharing options...
mfewtrail Posted December 16, 2013 Report Share Posted December 16, 2013 Mileage is going to greatly vary due to where you're driving and how you're driving. 90-95% of my driving is on the highway at 60mph most of the time. The more I do city driving the more mileage drops. Elevation is also not a big factor in my area so most of the roads are very flat. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted December 16, 2013 Report Share Posted December 16, 2013 Your right foot makes a huge difference. I can drive my Cutlass week after week, and get consistently 20-21 MPG around town. My wife has yet to do better than 17 driving the same car. Quote Link to comment Share on other sites More sharing options...
virtuetovice Posted December 16, 2013 Report Share Posted December 16, 2013 Yeah, my trips to richmond (2hr drive mostly at 60 mph) can average 28-30. Keeping it under 2k RPM's between 55 and 65 MPH is a good sweet spot. Other factors I have seen really make a difference is tire pressure, and full trunk vs empty trunk. Yeah if you have enough crap in your trunk, it WILL decrease your mileage. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted December 16, 2013 Report Share Posted December 16, 2013 weight in general has quite an effect. not so much on maintaining speed, but accelerating. for some reason, we had to transport 3 people in the back of the 90GP..... and none of them were under 250lbs. well, their combined weight caused the failing trailing arm mount to let go, in addition to taking HUGE amounts of throttle just to move the car. 3300lbs + 5 passengers that total up to around the 4,500lb range is quite a difference compared to 3700. that poor 4T60. Quote Link to comment Share on other sites More sharing options...
Luke94vert Posted December 16, 2013 Report Share Posted December 16, 2013 It's all in how you drive. The smoother you are with the accelerator,brakes, steering, the better your mileage will be. That being said I've gotten as low as 13 mpg and as high as 32 mpg throughout my wbody car history. On average this is what I've found with 75% city 25%highway 2.8 - avg 22 best 28 3.1 - avg 21 best 30 3100 - avg 23 best 32 3.4 - avg 20 best 26 3.8 series 1 - avg 19 best 27 3.8 series 2 - avg 18 best 34 (highway for 3 straight tanks) 3.8 sc - avg 16 best 28 I have not yet had the pleasure of owning a turbo, that may be coming this next year, so don't know on them and the 3.4 manuals I have well I have never actually checked. They get a lot more throttle cause hell it just fun. Lol. Quote Link to comment Share on other sites More sharing options...
RoyalRegal Posted December 31, 2013 Report Share Posted December 31, 2013 I get between 14-17, 95% city with a HEAVY foot. 1987 3.8SFI. I have the 4T440 (pre-4T60), so at highway speeds, I do pretty good (mid 20's). Quote Link to comment Share on other sites More sharing options...
Gibby Posted January 6, 2014 Author Report Share Posted January 6, 2014 Well I appriciate all of your info. I have been driving it like a grandma, no boost at all, slow acceleration, very conservative on braking. Taking into note that winter gas can possibly take away your gas mileage, I got a best of 21.8 mpg. Not sure if it will get better than that, this was a mix of freeway and town, about 70/30 Quote Link to comment Share on other sites More sharing options...
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