jstaneff

I've noticed this, and yes, it is probably quite obvious.

Sunday I drove about 25 miles and got about 27 mpg on a cold engine. Several hours later (3 or 4) I drove about 30 miles and got about 32 mpg. Air temp was about 63 F. This is by no means unusual. Very similar road and traffic conditions, just a longer route home.

I'm expecting that the car will get better mileage on a warm engine.

But, how to get it warm without burning gas? Or, how to keep the waste heat on startup close to the engine so that it does warm up more quickly? And how to keep the engine warm while it's running?

Does anyone have any ideas? In winter a block heater can keep the coolant from freezing, but I doubt that's sufficient to help mpg. Is there an add-on kit that basically insulates the engine compartment when the engine is off to keep heat in? I wouldn't mind plugging in (to the garage wall) to circulate water and run the radiator fan if it meant that the waste heat would keep the block warm and improve gas mileage.

Some of the super-mileage cars from the 1950s had super-insulated engine compartments, and got very, very high mileage. Is it reasonable to think that air moving across the engine is hurting mileage?

Hmm.

C300Sport

With the engineering put into these cars, there doesn't seem to be much you can do other than keeping an engine heater running(and that won't help much). I think you would likely spend more money on electricity than you save in gas…not to mention the hassle. It's simply a function of the car's electronic control running the mixture richer until it is up to operating temp. For most driving, you should be pretty well at optimum after 3-5 miles.
I have heard that some manufacturers are looking into preheated Cats but that is just for emissions and likely only on hybrids that have enough battery power for that.

e1000

move to Arizona

kevink2

Likely the 8 quarts of cold oil that is slow to heat up. For cold climates, a pad heater may work.

http://forums.viperclub.org/rt-10-gt...ck-heater.html

nyca

don't worry about it, gasoline prices are going to fall significantly as the recession takes hold - its already happening - regular gas was $3.08 in NJ today.

Vector02

I've NEVER had milage close to 32mpg! What speeds were you traveling? Setting the cruise on 75, I get like 27...

bigigg

i was gonna say.. how do u get 32 wtf.. i average 18 to a tank.. but i have 4matic

Spec_Davis

i need to know the speed your going so i can try to get the same MPG.

Untertürkheim

Have you tried increasing your tire pressure a bit?

Untertürkheim

You could make sure to keep the climate control off so as not to use the engine heat for heating the car, although I am not sure how much it will help.

Vector02

My cold pressures are +3-4 already! I don't do any aggressive driving, and I keep pressures pretty high.

mac911

Highest mileage I ever did was 29 MPG, and that was going 100+ miles nonstop at only 60-65. I think the surface of the road, gasoline in the region, etc. etc. all play such a big role.

I also wonder how bad front license plates hurt?

Most tanks I average 20 exactly by the way.

jstaneff

How did I get 32? What bothers me more is why I don't get it more often.

- Traffic stopped on the freeway, that'll lower mileage
- Long hills, that'll lower mileage
- Stop lights, that'll lower mileage
- On ramps, that'll lower mileage
- Driving too slow AND unsteady (e.g., not a constant speed) will lower it

All speeds and distances in miles ....

The trip I wrote about was 30 miles. The first mile was suburban streets to a parkway to a freeway ramp. There were 3 segments of freeway (2 interchanges). The first was fairly high speed, in the 50s. The second was in the 30s because of traffic and sharp turns.

My average speed for the 30 miles was 61. I kept it above 60 (except as noted above). That meant speeds ranging between about 58 and 72 on the freeway, with only the first segment near 70 (limit lowered half-way through it).



If I drive country roads at speeds between 35 and 50, I get mileage close to 30. To get 32 I have to drive faster. If I drive over 70, the mpg lowers.

I did that ECU reset at 7,000 miles; I'm now at 14,000 miles.

The car does have a front plate.

I'm not using the cruise to get this, and I'm not holding a stead speed. The actual speeds are traffic related, and I do try to keep it somewhere below 10 over.

I had one tank of "bad gas" and it took about two additional tanks to finally get rid of it. "Bad gas" probably means it had water in it; I got it in Olympia, the rain capitol of the whole bloody world!

The car gets better mileage when there's extra weight on board. This is odd. A full tank always gets better mileage. When the car's down to a 1/4 tank, a passenger helps. I'm thinking that the extra weight brings the car a wee bit closer to the ground, lowering the amount of frontal area and perhaps the Coefficient of Drag. Odd. (And a REAL reason to lower the car!)

The best I've seen is about 34.5 mpg, and on my usual commute route, but without "downhill with the wind". The secret appeared to be time of day and little traffic.

My usual is to get 29-31 on that usual commute. Even with this trip segment of 32, the tank will finish out at about 28.2 or so. (I cannot only drive freeway!)


As to the other ideas: a pan warmer is cool I wonder how much the one-time fire permit fee is? As to the engineering, I understand that the effort is very good; I guess I just want better

Carsy

In the old days people used to put a cardboard sheet across part of front of the radiator so the engine would warm up more quickly. A risky practise unless you monitor it very carefully. Old tractors had an adjustable damper at the front of the radiator for adjustment for ambient temperature conditions. I think I would not bother as your thermostat is probably very efficient at increasing the jacket water temp to the optimum in the shortest time frame.