All summer I read that that FE really improved as the car passed its 5000 mile mark and the engine "loosened up." Having picked up my car in early July and having just crossed the 5000 mile mark this week, I have to admit that I'm more inclined to believe that those observations were all a coincidence of timing.

I think most people just happened to correlate improving FE with having more miles on their cars, but they didn't take other environmental factors into account. I bet the owners that making the claims were largerly the group that purchased their car in cooler weather (winter/spring), racked up miles as summer approached, and noticed, that, "hey, my FE really is improving as I get more miles!"

I have to say that as the temperatures have dropped (only to the low 50s) here in the SF Bay Area, my FE has dropped noticeably too. After averaging about 49 MPG on my last 8 tanks, my 9th tank dropped to 46, and my 10th tank is looking like it will come in at 44.

Just like you read about in the block-heater discussions, my first 4-5 miles on a 40 degree morning are without any regen or auto-stop, which just kills me in stop-and-go traffic. On my 9 mile commute to work, I used to be able nurse it into the parking lot at 56 MPG during the warm weather, but now I'm lucky to get 48 MPG. The return home in the evening is worse because its slightly uphill.

I'm curious, is anyone right now seeing their FE improving as their engine loosens up around 5K miles EVEN though the temperatures have dropped 20 degrees ot more?

-dan

 

I did not have the opportunity, in my opinion, to notice a Engine Break in effect on my FE due to the major varying temperatures in my area.

Quite honestly, IMHO, Temperature is everything (in seasonal climates) with the HCHII in correlation with FE.

There is even a siginificant difference between -18C and -25C. I find that the Assist and Autostop features are non existant as the temp floats below 20C and pick up intermittently between -10 and -20C. I will average 6.5 L/100 - 9.0 L/100 in the extreme cold.

In the spring / summer (+10 C) I can average 5.5 L/100 and on a great summer day (+20 above) average 4.7-5.0 L/100.

Its all over the map and mostly dependent on the environment.

Hope that helps!

Regards!

 

I did see a good rise at about 5K, but I do admit it's now hard to keep mileage up the past week... since cooler weather started in So. Cal. I currently have 12,500 mi. on the car.

My vehicle was purchased in early April... hit about 5,000 in July or August, so warm weather was really with us well before the 5,000 mark. Could have been coincidence... or just driver training!

 

Good thing I'm in FL. Temps vary but its not as much as other places. I honestly think the better FE has to do with the drivers getting better at driving efficiently. There probably is a little from break in but most of it has to do with how you drive.... I've got almost 4k on mine and I feel good about the mpg so far.

 

I agree with you that the biggest factor for improving FE is the improving skill of the driver. But I think everyone would also agree that within a couple of tanks those skills have nearly reached a plateau. For me, this happened by 2000 miles. I was looking forward to this fabled continued improvement in FE people claimed finally peaked soon after 5000 miles. I continue to believe warming outside temperature really was the major force behind those claims - not so much the loosening of the engine.

I'll have a chance to test some of this around Christmas when we'll road trip down to Tucson, AZ. If it's anything like last year, the day time high will be in the 80s. We'll see if FE goes back to normal.

Also, don't the oil companies play around with the gasoline mix according to the season? Is summer gas and winter gas just a California thing? How does the different gas affect FE? Maybe it hits FE with the Winter mix.

-dave

 

Hopefully it does warm up and bit and you can enjoy 80.