EPA Mileage Estimates vs Real World

[timb]

Couple of comments -

Bird - if you're interested you can get the EPA ratings for your older vehicles right now on the EPA site - both with the original method and using the 2008 method.

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Dubba - I just couldn't remember off the top of my head if our 'summmer' mix was 10% ethanol - I believe that is the mix. Here's the odd one - my Cherokee does (very slightly) *better* on that mix than with the pure gas winter blend. I suspect whatever BTU/gal loss there is with the Ethanol is more than made up for by less idling/traffic in summer vs. winter weather.

OK you guys you seem to be reinforcing a suspiscion I have - the people who report the horrendous mileage tend *not* to be the ones who actually keep very close track - they're reporting based on a random fill up or two where they paid attention - or maybe just off the trip computer, again using a too-abbreviated measurement timeline. They may not pay attention to tire pressure - or keeping their vehicles maintained correctly over time. The folks who *do* keep track over a long time (and probably do a better job on average of dotting those other maintenance "i's") are actually beating or at least meeting the EPA numbers.

Here's where I'm coming from. Since our state govt. has seen fit to tie us directly to Calif. CARB standards here in PA for 2008 (we were not quite at the same level prior) - many engine choices have been removed - at least for this model year.

I'm replacing my 96 Cherokee with a new Grand. However, in PA - we have just two engine choices - the 3.7 gas six and the Hemi. You can't get the better 4WD system on the small six and you don't have much trailer rating. On the other hand the Hemi is overkill for me (not that it wouldn't be entertaining.) I was interested in the 3.0 CRD and as a fallback if I didn't care for that after actually test driving it - the revamped 4.7 gas V8. But neither engine is available here for 2008.

There are scary tales of bad mileage with the Hemi - but there are reports (again from people who seem to be keeping better track) - of much better numbers - above the EPA just like many of us have experienced. In fact - not that much different than I get with my 4.0 straight six. Not crazy about that but I can live with it.

So - just trying to get a comfort level on what I could *really* expect once broken in (and on synthetic like I run on all vehicles) vs urban legend.

 

[timb]

Measured miles and timed runs at 60 and that sort of thing - all of my speedometers and odometers seem pretty accurate. I haven't changed rolling radius significantly either with replacement tires so I'm pretty comfortable with my numbers.

I'm also *dang* sure the gas station pumps are not 'generous' with their metering (reading low) - if anything it would be the other way but I think they're pretty closely audited.

 

[MikePA]

I don't see why you couldn't do better than EPA numbers with the Hemi, provided you can keep your foot out out of it. Under light load and crusing, it deactivates cylinders, I don't think the other engine does that.

 

[Bird]

Thanks, Tim. I didn't know about the website for the older vehicles (I did have to edit your post to add one letter to get the link to work). So . . .

2001 Windstar
Old method city 18, highway 24, combined 20.
New method - 16 city, 22 highway, combined 18.
My actual combined = 19.857

2001 Ranger
Old method city 18, highway 22, combined 19
New method city 16, highway 20, combined 18
My actual combined = 18.777

When you consider the fact that (if you knew me), I'm not a hotrodder anymore, but I make no special efforts for better mileage, I accelerate briskly to merge onto freeways, moderate acceleration the rest of the time, drive the speed limit to 5 mph over most of the time, I guess you'd have to say the EPA ratings aren't far off.

 

[kenmac]

I don't see why you couldn't do better than EPA numbers with the Hemi, provided you can keep your foot out out of it. Under light load and crusing, it deactivates cylinders, I don't think the other engine does that.

Depends on which hemi you have. ALL hemi's don't drop cylinders

 

[MikePA]

Depends on which hemi you have. ALL hemi's don't drop cylinders

The one in the Jeep Tim is looking at does have MDS.

 

[milkman]

When Citgo was shut down in Ky. In. and Oh. and Marathon took over their stations in my area, my mileage dropped two miles to the gallon, might have been the same time they switched to the ethanol mix, but I haven't been able to get the mileage back up. I'm still getting what EPA estimates for all three vehicles, but it still chaffs me that I lost 2 mpg.

 

[jwstewar]

1997 Honda Accord 2.2 w/ auto 250,000 miles
Old method city 23, highway 30, combined 26.
New method - 21 city, 28 highway, combined 23.
My actual combined = 32 - 33

1999 Chevy Silverado 4x4 ECSB 5.3 V8 100,000 miles
Old method city 16, highway 18, combined 16
New method city 13, highway 16, combined 15
My actual combined = Around 19.5

2005 Chevy Trailblazer EXT 4wd 4.2 inline six 24,000 miles
Old method city 14, highway 18, combined 15
New method city 12, highway 17, combined 14
My actual combined = Around 14 - 15

I have a pretty heavy foot and like quick starts. Usually don't have too much of a problem beating the EPA estimates - except for our Trailblazer. Once you get it rolling it does OK, but man it sucks the gas to get it moving. I told Monica I wanted the V8 because I thought it would have done better on gas, but we couldn't find one at the time. Needless to say the Trailblazer sits in the garage most of time. I drive the Accord and Monica drives the Silverado. We both like driving the truck the best, it is the most comfortable with the most room.

Another thing I've noticed with my mileage. People say gas is gas, well I don't agree. If I run Shell I get better MPGs. If I put in Speedway/Marathon I get crappy gas mileage and sometimes the vehicles feel like they won't run well enough to even get out of their own way.

 

[dbdartman]

EPA says my 04 Colorado 4WD should get 16 city, 21 highway. I regularly get 17-18 in my "usual" driving (2 mile round trip to dump twice a week & 12-14 miles one way to suburban Trenton 1-2 times/month). On road trips it'll get 25-26. This is with the optional 3.5 5cyl engine, auto trans, extended cab, Leer fiberglass cap (same height as cab roof), & optional 3.73:1 gears. I couldn't see running taller gears in this as it's only turning 1600 RPM at 50 MPH now, around 2000 RPM at around 70! The computer has been "tweeked" some (running the premium fuel ignition curve with 4 degrees pulled out across the board, torque management disabled, red line & shift points raised about 225 RPM, & line pressure in trans raised slightly). I generally drive pretty sedate, but matting the gas pedal isn't all that unusual either. I don't check the mileage every fill, but do it often enough to feel comfortable with my numbers.

 

[HUCKthe1]

Timb,

Do as I did if they don't sell the vehicle with the engine that you want in your state. Buy it where you can get what you want then register it there in PA. I had this problem because NY does not sell diesel cars (but trucks are okay?) so I purchased mine out of state and took it home.

I understand the push for better emissions but look at the lost of fuel economy too. Cars should be getting better fuel economy than they did 10 -20 years ago. Even though they are better now, I feel they are far from where they should be. Cars in Europe get 40 to 50 MPG on average.

Oops I wasn't going to let my conspiracy feelings get involved.