I have a 2009 Chev Equinox with 18K miles. On a recent highway trip, I got only 22 mpg (only 2 people in car, used cruise control, wasn’t hauling a horse…) - the dealer sticker claimed this car should get about 32 mpg on the hwy! The dealer’s service manager told me: 1. the mpg figures are not based on reality; they are only to satisfy the Feds (his actual words, not mine) and 2. the only way I could hope to get near this mpg figure is to inflate my tires to over 40 psi (which is not how they are rated). I am shocked! This vehicle’s gas consumption is not much better that the 1983 S-10 Blazer I lost in the Katrina flood. And THAT car had 190K miles! I’m looking for helpful suggestions or similar - in the meantime, I’ve convinced them to do a diagnostic on it next week. thanks for reading my post!
The service manager is full of crap. Talk to the owner of the dealership and tell him you bet “the feds” would be really interested to learn that a GM service employee is admitting they lie on the EPA sticker. 
How fast were you driving? was there snow on the road? How many actual miles did you drive? Are you sure you started measuring the tank with a completely full tank and you filled it at the end to determine the actual volume used?
That seems low. How did you measure this, exactly? Are your tires inflated properly?
How were you measuring the mpg? Do you have the 2.4 or 3.0 engine? How fast were you driving on the highway? Above 55-60 mph the highway mpg will start dropping quickly. The Avg Mpg and Instantaneous Mpg figures on the dash display are useful, but should not be taken as gospel.
I track the miles and gallons at each fill up. Every fourth or fifth fill up (~1000 miles) I add up the miles and gallons to calculate the mpg. My actual mileage is usually a little lower (.5-1 mpg) than the calculated Avg Mpg.
Ed B.
For a model with AWD it’s rated 16 MPG city 24 MPG. On the highway If your Equinox meets that discription then 22 MPG on the highway would be reasonable.
The FWD mode is rated 17 MPG city and 24 on the highway.
This was no 4 cylinder Eqinox in 2009, and there was never a 2009 Equinox rated for 32 MPG. The redesigned 2010 model could be had with 4 cylinder and it was indeed rated for 32 MPG highway. But OP has the older 2009 model, which is a different machine.
There is likely nothing wrong with the OP’s car as he’s getting pretty much the kind of mileage one can realiticalyl expect.
I’m one of those stay-at-the-posted-speed types, so I’m sure that’s not the issue (LOL); as for the calculations: I did start/finished with a filled-to-the-top tank and tracked the 1200 or so miles on the trip-ometer. No snow, but cold - could that have been part of the cause?
that’s a good idea, Ed. I’ll try that!
Once again very nicely handled.
actually - my mistake, it IS a 2010…
anyways–since you seem to be the source of all good details, what is your take on the 40 psi tire advice?
40 psi would be over-inflated. You might get better mileage but handling and vehicle safety is decreased. Not a good idea. Check the placard on your vehicle for the proper tire inflation pressure.
?? do you two work for GM or something? thanks for giving me a laugh!
that was my thinking - but the service guy claims he over-inflates the tires on his and his wife’s car. But maybe he doesn’t like her? LOL
No I don’t work for GM, but I did work for Nissan and then later Ford. I prided myself on having good product knowledge. Though it seems that most salesmen these days don’t. Also I would also advise against the 40 psi plan. Just go with whatever the manual/door jamb says.
For the 2010 model if you have 3.0L V6 AWD model, then it’s rated at 17 MPG City and 24 MPG on the highway. Again 22 MPG would be reasonable. If you have the AWD 2.4L I4, then you should be getting 20 MPG city and 29 highway. In that case 22 MPG on the highway would be low, but a combined average of 22 MPG wouldn’t be outrageously low
For the FWD model I4 is the one that’s rated at the vaunted 32 MPG highway. The V6 FWD model is rated for 17 MPG city and 25 highway, and 22 MPG would be in the ballpark.
Basically is you have the I4, then your mileage is a bit low, if you have the V6, then you’re doing fine.
but the service guy claims he over-inflates the tires Then he is right, he is over inflating them.
Cold will account for a 2 or 3 mpg drop. 5 if you’re really unlucky. I’ve never seen it cause a 10mpg drop.
The thing is that the service manager said “Oh the ratings are a lie.” If she were indeed getting the mpg indicated on the EPA sticker then the service manager should have said “Actually, here’s the EPA rating, and you’re getting it.” That he did not tells me that there’s likely a problem. That he lied about the ratings being valid tells me that he knows there’s a problem, it’s expensive, and he doesn’t want to deal with it.
The thing is that 32 MPG claim only applied to a specific model (4 cylinder, 2WD) If OP mentioned what model he had then it would be easier tell what’s going on. If he/she has the V6 model, then 22 MPG in in line what he/she should be getting and there probably isn’t anything wrong with the car. If he/she has the four cylinder then the may be reason for concern.
Glad to know someone is reading all those technical bulletins and manuals! thanks for all the info! and thanks to everyone who took the time to respond.