Originally Posted by Doru (Post 995017)

Winter gas has a different blend than summer gas, and mpg will suffer.

Originally Posted by TiAgX5 (Post 995032)

Summer fuel blend AND running AC knocks my full tank city miles from low 400s in the winter to around 350 in the summer. Almost a 20% reduction.

Originally Posted by Doru (Post 995037)

Also, in winter the drive in the city is MUCH slower, more frequent & longer stops at red lights, plus some idling. This on top of different fuel. So it could add up to 20% or better.

P.S.: plus the car drives longer with the engine at non-operating temps until it fully warms up.

Originally Posted by bcredliner (Post 995018)

Symptoms of bad ccv can be rough idle, oil consumption, oil smoke on startup and loss of mileage. Worst case is engine lockup.

Originally Posted by puddinboo (Post 995042)

mine did all the above lol. this winter.

Originally Posted by puddinboo (Post 994819)

is it possible that a bad ccv that is freezing up in the winter months give bad gas mileage? right now I`m getting 13.7 l /100km city and in the winter was about 17l/100km city.

Originally Posted by Helihover (Post 995039)

Very intrigued by your conclusions. Care to share your factual results which brought you these conclusions?

Maybe you misread? He's getting worse gas mileage in the summer.

Typically cars get better gas mileage in the summer.

Originally Posted by bcredliner (Post 995118)

Where on Earth are you located?

Originally Posted by Helihover (Post 995168)

Ahh forum talk........

So after rereading the op 5 times I think he is saying he's getting better gas mileage now that the temps have come up? Sweet, this is normal.

And now I think I'm reading that some are saying that summer blends tend to yield worse gas mileage?

I don't know anymore..

But I do know this: "winter blends" contain additives, AKA fillers, AKA less combustible material, AKA WORSE fuel mileage.

Here ya go. Straight from the intraweb (so it must be true), honestly though this is only one example of hundered's of articles that all have the same conclusions.

Hello Topspeed,
My car gets better gas mileage in summer than in winter. Any idea why?
Robin K. from Stamford, Connecticut



Hello Robin,

There are many factors that cause cars to achieve better gas mileage in warm weather. It is mostly due to the fact that cold weather, especially winter weather, negatively affects fuel economy in general. Some cars, such as hybrids and electrics, are affected more than others but this article will only address gasoline powered cars.

Here are nine reasons for why cars get better gas mileage in warm weather:

1. Oil Viscosity

Oil viscosity (thickness) is affected by temperature. Heat reduces oil viscosity (makes it thinner). This reduces drag on the engine and increases gas mileage. Cold increases oil viscosity (makes it thicker). This increases drag on the engine and reduces gas mileage. An engine operates more efficiently when the oil flows like water and not molasses. This concept also applies to all the other lubricants and fluids found in your vehicle.
E53s use multi weight oil intended to keep the viscosity consistent regardless of the weather--N/A

2. Tire pressure and rolling resistance

In fall and winter, tires lose air pressure due to the colder weather. Under-inflated tires increase rolling resistance and decrease fuel economy. In spring and summer, tires gain air pressure due to the warmer weather. Rolling resistance decreases and fuel economy improves.

This assumes winter tire pressure is not adjusted which is not true of all X5s. Since it is preventable it is N/A to this debate.

3. Engine warm up time

Modern vehicles achieve peak fuel efficiency only when they have reached their normal operating temperature. In colder weather, this process takes more time and results in decreased fuel economy. In warmer weather this is not the case. Your engine reaches normal operating temperature faster and fuel economy improves.
This assumes winters are cold everywhere. Since that is not true it is N/A to all environments

4. Air density

Hot air is not as dense as cold air and it presents less resistance to the forward movement of your vehicle. Consequently, your gas mileage will be better in warmer weather.

Once again this depends on the range of temperatures from summer to winter which varies by area. In some regions density is more than offset by loss of engine power, neither happens everywhere-N/A

5. Ice and snow

Ice and snow, which commonly accompany cold weather, create slippery road conditions. This often causes wheel spin upon acceleration. A lot of wheel spinning also occurs when trying to get out of icy or snowy parking spots. All this going nowhere reduces your gas mileage. Furthermore, ice and snow force you to drive at less fuel efficient speeds.
There are places where winters are seldom below freezing and folks that have ice and snow should know that spinning the tires is counterproductive especially with 4 wheel drive and DSC. This is also not something that can be considered as a worldwide factor to endorse ones position.

6. Cold weather starting

It usually takes longer to start a vehicle in colder weather. In the middle of winter, poorly maintained vehicles can spend several minutes trying to start up. While the engine cranks, gas gets wasted and fuel economy decreases. Vehicles start faster in warmer weather which results in better gas mileage.

How long it takes to start an X5 should not vary except perhaps in extreme conditions. Since winters are not extreme in all places and how a vehicle is maintained is not consistent across all X5s this should not be used as a point of endorsement.


7. Winter grade gasoline

Here in America, many states require gas stations to sell oxygenated, reformulated, or blended gasoline during the colder months of the year. These types of gasoline often contain ethanol or butane, and this diluted gasoline will typically lower your fuel economy by one to three percent due to its lower energy content. Gasoline sold in warmer months has a higher energy content which results in better gas mileage.

The requirement of many states is not the requirement of all states nor worldwide. In addition, gasoline is blended regionally, any mileage impact is not something that applies to everyone and therefore not applicable to the debate.



8. Increased alternator and engine load

Drivers use more vehicle accessories in colder weather than they realize. The heater, the defroster, windshield wipers, electric seat warmers; all this puts an additional strain on the alternator. This demand on the alternator creates additional drag on the engine which reduces fuel economy.

Alternator "drag" does not vary. Air conditioning does increase drag on the engine. That said, the point does not apply to every E53 so it is a not starter.

9. Better vehicle maintenance

Many people are in the habit of tuning up their vehicles in preparation for travel during spring and summer. It is no secret that a well-maintained vehicle gets better gas mileage than one that is neglected.

Many of the forum members maintain their X5 the same regardless of the season. Since Many is not all the point is N/A.

Well, there you have it. Warmer weather equals better gas mileage. We can all move closer to the equator or we can wait until technology develops engines that are more fuel efficient in colder weather. Now wouldn't that be interesting?

Originally Posted by bcredliner (Post 995334)

My point is that there is no universal answer to the question. It depends on a myriad of variables even in a small region.

Originally Posted by TiAgX5 (Post 995032)

Summer fuel blend AND running AC knocks my full tank city miles from low 400s in the winter to around 350 in the summer. Almost a 20% reduction.

Originally Posted by TiAgX5 (Post 995390)

First post stated over 400 miles per tank. Slightly over 3% overstated loss is close enough for internet forums.

Originally Posted by Helihover (Post 995361)

Wow!:). It's all good. I can't agree with your alternator load though.

TiAg please re check your math. 50 is 12.5% of 400.

I'm not trying to start any debates here. It's just my common sense detector going off. So I'll repeat. You will not see a 20% increase or decrease in fuel mileage from different blends of fuel sold at public gas stations. C'mon guys, 20% is HUGE.

You guys are great:)