I finally remembered

For a few years now I’ve had many questions to ask the Car Guys but never did, since becoming a site member I had a couple more questions but only was reminded of them while in the car (never while in front of a computer).

Well I finally remembered to list my questions:

  1. “Trac Off” - What exactly does that mean and what effect does it have on handling and gas milage?

  2. Is there any difference whatsoever in gas consumption if the AC is on high vs medium (do not factor in climate control) for a 1000 mile trip?

  3. ‘Fog Lights’ - when there is thick fog are we suppose to turn off the headlights and just use the fog lights? Are running lights suitable fog lights?

  4. Road Turn Protocol - The two-way two-lane road you are on converts to a two-way one-lane road at the intersection, you want to make a left turn, and the on-coming car also wants to make a left turn at the intersection, when the light turns green what should happen:

a) both cars turn in front of each other,
b) both cars turn behind the other,
c) one-lane car should wait for two-lane car to turn,
d) two lane car should wait for one-lane car to turn,
d) some other answer

Please tell me your opinion even if you don’t know the law or road Etiquette.

  1. Transmission Shifting - when driving a standard shift car we let up off the gas before and during clutch engagement; does this also happen when driving a an automatic? If so do we lose that small amount of gas that continues to flow while the clutch is engaged?

  2. At times I see a stream of liquid flow from the tailpipe of a car about to enter highway traffic, is that unburned gas? If not what is it? I notice it alot in the mornings, could it be an accumulation of some other liquid if the car isn’t properly warmed up?

  3. Warming Up The Car - is there a difference between allowing the car to idle in place or allowing the car to move on it’s own – no acceleration whatsoever (moving about 3 miles an hr for about 1/4 mile) during the warm-up process?

  4. Long ago my gas float ‘thingy’ died, when it was replaced I was surprised to learn that this electronic instrument was in my gas tank, and actually and more surprised to learn that running your car low on gas too often ‘burns’ the float/gauge/monitor/thingy it out faster. Why is there an electronic thing IN my gas tank?

  5. Has anyone ever seen a wood, metal, or spray-on headliner?


  1. Given the massive flood damage Katina and Sandy has done to millions of cars shouldn’t it have impacted (lowered) the prices of used car parts?

No.4- if in doubt surrender right of way
No.7-Yes,but very little
No.8-best way to do it
No.10-market wont allow it

#3 Fog Lamps:

First, the common error.  The color yellow does <b>not </b> help you see better in fog! We have been using yellow lamps for many years without any data or good theory to support using yellow.

Of course you first really need to define yellow.  What do you mean by yellow or white? 

Did you know that if you mix the right amounts of yellow and blue light you get what???  You get white! 

 If you really want to mix things up, then you need to look at what those terrible orange or blueish lamps used on the  freeways do.  Look at the color of your car when driving under those two types of lamps.  Our eyes were designed for natural light sources.  I don't think God (by what ever name you use for him) designed them seeing on the freeway with those blue or orange lights. 

 While in college I both studied physics and light as a student and professional photographer. 

 I found it very interesting and for me my studies were supported by my profession and the the other way around.  

 Car manufacturers are not interested in providing the best lighting, but rather they are interested in selling cars.  If a gimmick will sell yellow lights or blue lights they will sell them.  They will not bother telling you that they are not providing you with the best lamps for driving. 

Now for turning off the headlamps.

That will depend on the car design (placement of the headlamps) and a few other factors.  In general, you want to have less light reflected from fog back to you.  Light tends to be reflected directly back from the source.  having the fog lamp a little higher or lower to the road can make a big difference. 

 I suggest that the next time you get a really good fog, pull off in a dark safe area and experiment.  You don't even need a car.  Get a good flash light and try holding it over your head, then while keeping the beam on  the subject, move the flash up up and down from as high as you can reach back down to the ground.  

 The best example I have had was my old Miata with the pop-up lamps.  In a deep fog could see much better with the headlamps off using only the low mounted fog lamps and then turn on the head lamps. I could change the direction of the lamps to see exactly what was happening and how it effected what I could see.  

 For those who don't know me, might want to know why I hit so hard on this issue.  Back in the old days, just a a month after getting my driving license on a foggy morning on I- 70 in Ohio I was the thirty first vehicle in a 31 vehicle double fatality accident.  I was lucky and only lost two teeth.  Sorry for preaching.
  1. Traction control is turned off. The car will no longer try to prevent your wheels from spinning. Sometimes you want this if you are stuck in snow or mud, when wheel spin can help you.
  2. No measurable amount.
  3. If you have fog lights, use them with your low beams. Do not use high beams. You will only blind yourself.
  4. There is usually enough room for both cars to turn left, but if in doubt, surrender right of way.
  5. With a manual, you want to synchronize releasing the gas and engaging the clutch to make the shift as seamless as possible. This should come naturally with practice. An automatic is completely different and needs no such concerns.
  6. It’s water. Water vapor is the overwhelming majority of the combustion process. Due to condensation, we see more of it in the winter.
  7. It’s best for the car to warm it up by driving normally, but gently. It speeds things up quite a bit.
  8. It’s in there because it’s easier to push liquid at higher pressures than it is to pull it. Also, the pump is completely submerged until you run completely out of gas, so the “burning it up by running it low on gas” thing is unlikely, but it is a good idea for many other reasons to not run too low on gas.
  9. Can’t say that I have.
  10. If anything, this type of event will cause prices to go up.

Fog Lights - most of the fog lights that come on cars, trucks, and SUV’s from the factory are worthless. They are for looks and to jack up the price but aren’t effective. All of them only go on only when the low beam headlights go on. Then the low beam headlights produce glare off the fog and negate any benefit from the fog lights.

You can buy effective aftermarket fog lights. They should be mounted as low and close to the ground as possible. They should not be too bright, and many use yellow lenses to help cut through the fog. They should be wired to work when the low beam (and high beam headlights) are off. The disadvantage of low mounted fog lights is they are easily damaged when parking.

Factory installed fog lights might be effective if you change the wiring and put a switch into the circuit to power the fog lights independent of the headlights.

For number 1, to expand on what mark9207 said, traction control will reduce power to any wheels that are spinning. In most cases, this is what you want to generally keep the car under control (so you should leave it turned on). However, if you’re trying to climb a snowy hill, this may reduce your momentum to the point that you can’t get up the hill. In that case, you can try it with traction control turned off, although you’ll probably need to make some quick steering adjustments to keep the car pointed in the right direction as different wheels gain and lose traction. Your owner’s manual should say something about this.

There’s no effect on fuel economy.

If the A/C comressor is engaged at all, it has just one effect on mileage. It’s either ON or OFF . the compressor doesn’t care what you do inside with the fan speed or temp.

True FOG lights are a technical matter dependant on beam SHAPE ( wide & flat ) and propper aim ( down in front ).
The intent of true fog lights is to NOT illuminate the cloud in front of you but to illuminate the ROAD surface so you get reflective light coming towards you through the cloud to see the road through the cloud.
FOG lights are a great addition in rainy weather to light that road …right down there in front of you. While driving lights are a taller beam aimed out beyond your dims, fog lamps should be aimed close to the vehicle.

Fog, even thick fog does not go all the way to the ground. Fog lamps should be mounted low and skirt the surface of the road, that way the light will not be reflected off the fog into your eyes. All the rest of the previous info about fog lamps is also true.

You turn in front of the other vehicle that is turning, but only after all through traffic coming at you has cleared. There are intersections around here where the left turn lanes are marked all the way through the intersection and they curve in front of each other, not behind.

Warm up your car by driving gently. You can go more than three miles an hour, just don’t stomp on it till the gauge needle comes up. The car needs to move to get everything warmed up at once. In sub freezing weather, if I don’t have to clear my windshield, I will be a half mile down the road doing 45 to 50 a minute after the engine starts. Hasn’t hurt the current daily driver in 254k miles yet.

Low fuel level will not hurt the sending unit for the gas gauge. Typically it is located high in the fuel tank so it isn’t covered by fuel anyway. The fuel pump is located in the bottom of the tank and is cooled by gas, but as long is it is pumping gas through it when running, it is being cooled. The outside of the pump does not have to be immersed. Unless I’m on a cross country trip, I wait until the needle is all the way to E and the fuel light is on before I fill up, again it hasn’t hurt the daily driver for 254k miles, still has the original fuel pump.

Natural disasters tend to take cars off the market, The insurance companies only pay out the current value of the cars as used cars, even if they were brand new a week ago. That means less cars available and a sudden influx of people who need replacements for the vehicles they lost. Lower supply, higher demand equals higher prices.

" Traction control off " is misleading in some vehicles. It turns it “partially off” if you will. The computer no longer cuts the throttle which may encourage wheel spin but, the abs brake system that helps the wheels on one axle act as a limited slip differential, still work. Theoretically, both wheels should spin if traction gives way but with equal torque applied to each.

This is the setting used by off road vehicles on all 4 and by front drive vehicles on the front two wheels. This is to allow maximum effect ness in deep snow or mud. When the trac is turned off on my off road vehical, all 4 wheels will spin, with equal torque…theoretically. That’s good for getting unstuck, but not so good keeping you on the road at higher speeds. Some vehicals more accurately call this switch the “stability control off” switch.

I’m pretty sure on my car the fog lights will work if I just put on the parking lights

dagosa wrote:
Some vehicals more accurately call this switch the “stability control off” switch.

I’m afraid I disagree. Although I know terminology varies here, I’ve generally seen “traction control” used for a system that simply cuts power to prevent wheelspin and “stability control” used for a fancier system that has sensors to determine where the car is actually being aimed and that brakes the individual wheels as needed in order to keep the car pointed that way.

WOW, i learned a whole lot (as usual here) thank you all.

New Question:

Is it ok to drive in OVERDRIVE gear all of the time? Or will it lead to over consumption of gas when under 50 mph, will it lead to premature aging of that gear, or any other problem.

In that same line of thinking, is it better to use 1st and 2nd gear often, and if so exactly when.

Holy cow. Well here’s my humble opinion:

  1. Trac control is just reverse ABS. It’ll brake the wheels to prevent spinning on ice.
  2. No difference. The compressor is either on or off (cycling) turn it as cold as you want.
  3. Fogs: Actually I think they are worthless except they look nice and people see you better. The idea was that they are lower to the ground so they don’t reflect back snow or fog as bad. Even though on my cars, the buld is the same size as the headlights, you can’t see crud with just them.
  4. A. Just make sure the other guy has the same idea. My driver instructor said don’t assume.
  5. No comprende. Just step on the gas steady.
  6. It is moisture condensing in the exhaust. The hot air is squeezing the moisture out of the cooler air in the exhaust system. Cold air is more dense so hot air can hold less water. That’s why planes fly better in the cold dense air. Physics 101.
  7. Everyone has a different opinion. The idea is to allow some lubrication before stressing the parts. So I start up, let it idle for a few seconds while I put my belt on and drive moderately for a mile or two. Anyone ahead of me going 3 mph is in trouble.
  8. Just like in your toilet tank, there is a float measuring the height of the gas, translated into voltage readings to the gauge. With no float, there would be no way to tell the height of the gas in the tank.
    9 Nope
  9. I dunno. Market forces, but its a big country. OTOH, I think most of these cars will be crushed and even if not, what good parts would there be? Maybe some sheet metal but not electronic, engines, trans, etc. I think I would be very careful buying used parts or used cars for a while.

I’m sorry I didn’t read everyone else’s answers first but I’ll go take a look.

Thanks again, its reassuring to hear the same thing said different ways, not just for the different perspectives or opinions but also to fill-in some info gaps, to smooth out some rough understandings, and solidify the nuanced

I will actually modify a lot of what I do because of your help – thanks again everyone.

When you use the word “overdrive”, that can have a lot of meanings. Overdrive simply means that the output shaft of the gear set turns faster than the input shaft. when the output shaft turns slower, that is “underdrive”, a term not used very often, and when they both turn at the same speed, that is direct drive.

Until the gas crisis of 1973, all American transmissions had a direct drive high gear. An overdrive was an optional gearset that was attached to the transmission to lower the engine speed. some of these, if not all, would also freewheel when power was removed. They were used to get the absolute best gas mileage for people who did a lot of highway driving, such as a traveling salesman.

I have only seen one car with this feature. The overdrive was engages by pulling a cable out, like a manual choke. As I remember, it could not be shifted when the vehicle was moving so you would select it if you were going to drive on the highway and deselect it if you weren’t.

When overdrives started appearing on vehicles after the gas crisis, there were a number of variations. With some of them, you could use them all the time except when pulling a trailer. But all of the overdrives then were an additional gearset in or added onto the transmission and were operated by the gear shift. On automatic transmissions, the transmission would select the overdrive gear just like it would any other gear, when the conditions were met for it to be selected.

For manual transmissions, the overdrive was basically a fifth gear, and again, when you were up to speed, you just selected it. It became known as fifth gear and not even called overdrive. I don’t think there are any automatics that call it overdrive anymore. Some have labeled it something like D4 where the direct drive gear is D3 or something like that, but now I think most, if not all just call it D or drive. There are a lot of variations now on this such as a side slot with + and - to move it up or down a gear and the traditional 1, 2 and maybe 3 positions.

And of course now there is the growing popularity of the CVT. Don’t ask me about that, the technology is too new for much information to be out there, other than the general principles.

Tom and Ray had a very funny article about overdrive a few years ago.

I’ll see if I can find it.

1979 Chevy short stepside pickup.
thm350 3-speed auto…I WISH it had overdrive.

KG,install a hone-a-drive,I suppose you can still get them,a lot of older Fords in the 60s had overdrive-Kevin

@Lion9car…traction control in both my older RAV and 4Runner cuts power when wheels spin excessive. The stability control also uses the brakes and the throttle, you are right. My manual cautions that when I lock my differential, it deactivates the stability control COMPLETLY and dis allows throttle to be cut. The traction control minus the throttle interupt is “always engaged” I repeat, it’s more acurate to call it stability control off. Those fancy sensors you allude to are deactivated too. When I lock lock the differential, I can do donuts. You can never do it with the stability control on.

Consumer reports even down grades vehicles that cut the stabilty control off when pressing trac deactivation or activation button. On all Toyota pick ups, when the auto limited slip is activated, the stability control is deactivated including the throttle limiter. Please look at this forum with this topic discussed by people who own these vehicals.
This is just a sample of one brand.