MPG ratings

You wont and never will. they do it on a dynameter with no load, no cold start ups either

I've always achieved very close (within 10% and often closer) to the highway mileage with all of vehicles I'ved owned in the last 20 years. Then again, I drive mostly on rural highways, stay pretty close to 55 MPH and don't accelerate and brake like a maniac.

Matt

I've been monitoring my Crossfires milage. It was rated 17 city, 27 highway. Overall, in the first 15,000 miles, I've averaged 25.3 which is reasonably close for combined city/highway.

The last 3 new cars in my family (1992 Dakota 5.2L, 1993 Vision TSi

3.5L, and 2000 Durango 5.9L) have all gotten a few MPG BETTER than the EPA highway rating, and were almost spot-on for the "combined" rating. The Dakota, in particular, just blew the doors off the EPA highway rating. Nearly 5 MPG better. Of course, as they say, "your mileage may vary." :-)

What combined rating? I don't recall seeing this on any window stickers. Is this a new EPA rating?

Matt

We have a 2005 T&C with 3.8 engine. It is rated at 18 city 25 highway. We have about 5000 miles on it. On a long highway only trip where we averaged about 70mph, we managed just over 24mpg. Not bad. We have never been able to get near the 18mpg city rating. We usually get about 15 or so. In combined driving we get about 17mpg.

-------------- Alex

We have a 1999/70K miles with the same engine and my wife gets between 13 and 14 around town. We can get 26 or so on the open road at 55MPH, but higher speeds decrease mileage.

Bob

The 300C does better then Consumer Reports says but worse than the sticker. EPA of the car is 17 city, 24 highway. I'm averaging between 16 and 17 so that's pretty close but that includes highway driving. On short trips, 7-8 miles, it gets 13 which is awful but better then the 10 that Consumer Reports says it gets. On long highway trips (100 miles) I get around 19. On a single occasion I managed to peak at 23 on a highway trip.

For ALL of you out there with a factory installed trip computer that will read "Instant Fuel Economy", I strongly suggest you put it in that mode and learn to drive by it. It is HIGHLY revealing as to fuel economy and how it is affected by driving style and sitting in traffic.

It used to be that the bulk of Chrysler's factory trip computers (especially on the LH cars) would read "Inst Eco", but in the later years it seems that this function has been deleted on some vehicles. Of course, all of them have "Ave Eco" readings, which can help as when you punch "Reset" at particular times, it'll first give the "instant" reading and then settle back in to its "average" cummulative readings.

On the Charger R/T I rented (an upgrade from a Taurus) recently, I found it interesting that you had to get the upgrade steering wheel controls to get the trip computer.

Now, back to the city driving fuel economy ratings and driving style. If you have the "Inst Eco" feature, you'll notice single digit numbers when pulling away from a stop sign, usually until you get into 2nd gear and then it'll go to about 12mpg until you get to crusing speed, back out of the throttle, and stabilize the speed. Being stopped at a stop sign or red light or fast food drive-thru all impact the fuel economy much more than you'd suspect too.

The difference in a 6mpg acceleration (reasonably brisk) and an 8mpg acceleration (slow) is not that different, but the 6mpg acceleration will get you to your desired speed . . . AND the more economical cruising speed . . . quicker such that overall fuel economy is increased. Hence, less time spent in lower fuel economy areas and more time spent in higher fuel economy areas.

Modern cars and trucks will coast much farther than you'd suspect too. Remember the old fuel economy tip of anticipating stops? Well, when a fuel injected vehicle coasts, it also goes deeper and deeper into "fuel shut-off" mode. So, use the quicker acceleration to get to the desired town speed, try to get in the traffic pattern that will let you hit all of the lights on green, and if you see slower traffic ahead, take your foot off the accel pedal and let it coast rather than driving right up to it and then using the brakes. The longer you coast, the more fuel is taken out of the system, up to an indicated reading of 99mpg on the computer display.

Also, using the factory cruise control is a boon to trip economy. Especially on the more finely controlled current era vehicles.

Once the cruising speed is reached, the computer will keep the vehicle speed highly constant. It'll throttle into the engine going up hills (sometimes as low as 15mpg), then trim the throttle back IMMEDIATELY as the hill is crested, and then also back out of the throttle going down the other side (going into "coast" and the resultant "fuel shut-down" modes). If you try to "foot drive" it, we all will try to maintain the speed up the hill, but forget to back out once we get to the crest and then head downward. The higher speeds reached at the crest and on the downslope, before we realize we're going too fast and then back out of the throttle, are not as economical by a significant amount as letting the cruise do the work. This is highly apparent when you try it both ways and watch the "Inst Eco" readings!

At cruising speed, the difference in 30mpg and 22mpg at the same speed is a very minute difference in pressure on the accel pedal. Not like it used to be with carburetors! On the modern fuel injected vehicles, as soon as you put more pressure on the accel pedal, it's feeding additional fuel "right then" rather than letting additional air flow through the carb venturi pull the added fuel into the intake air.

I never did get what I'd call a decent mileage check on the Charger R/T HEMI, but it's probably right at posted EPA Highway on the highway. Using the cruise at approx 65mph road speeds.

There's a posting in the LXForums website on how to rig a light to tell when the Hemi's MDS system is operating.

Bad thing is that a

Quite an extensive and thought-out write up.

I am surprised, with all the detail you did go into, that you did not mention affects of the cruise control downshifting to maintain the setpoint window on rolling hills terrain - particularly since you mentioned owning LH cars which definitely do this (to a point of annoyance at times, though it is better than getting tickets). Of course it is bleeding off energy that has to be made up when the terrain levels out and slopes upward again, and that costs gas mileage just like braking to accomplish the same thing would.

But if you weren't in cruise control, you would be having to either manually downshift or use the brakes to keep within the same ticket-avoidance window that the cruise control is attempting. I find that to really be safe from tickets, I have to take manual control in some way - usually I use your anticipation technique and move the setpoint down 2 to 4 clicks (depending on the amount of slope - 1 mph per click) before starting on the downslope, and I still get the inevitable energy-robbing downshift, but I force it into play earlier by dropping the setpoint (and bumping it back up at the bottom of the hill)

- otherwise I find myself at risk of a speeding ticket. Maintaining the same setpoint and letting it drift upward in speed 5 to 7 mph to gain fuel economy over the risk of getting a ticket would make as much sense as running red lights for better fuel economy. So it's another economy-killing reality that we gladly put up with to reduce/eliminate insurance rates and fines.

I also find the 'up' (2 mph per click) and 'down' (1 mph per click) speed settings adjustment to be *very* convenient for some of the reasons you said and what I added above. If I want to bump up 1 mph, without even thinking, I click up once, and down once. In extreme cases (steeper slopes), I manually downshift ahead of time (pretty much the same effect as lowering the setpoint). And, I find myself with my foot off of the gas pedal and using the cruise buttons to fine tune my speed during most of my mostly-55-to-60-mph-40-mile-each-way daily commute (using the gas pedal only for the occasional stop light and one small town that I pass thru).

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')