Do cars behave the same day in and day out? Or....

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Jul 7, 2008
I mean, they should behave the same... right? It's a CAR!! Not a fickle person! Yet, my experience with my car has been that there are those times when it feels more responsive, the engine more eager to rev, the steering wheel more eager to turn (less stiff) and feels like it handles better. Then, there are those days when it feels less responsive, more sluggish, the steering wheel feels harder to turn, feels like it doesn't want to handle... Thankfully, these days, I am getting more of the former behavior and fewer days where it behaves like the latter. When I first got the car, it was the other way around and I was deeply unhappy feeling that I had made the wrong purchase decision. The car is a 2007 Corolla CE 4SPD automatic, with 65K miles. I'm using 0W20 Toyota. I can't put my finger on it... I can't say that its' correlated with the weather. The best predictor of good behavior is when I use the local full service Mobil Gas station. Thus, I always go there, but even then, I get the occasional "bad" day. Is this normal? Am I crazy? Chime in, pls.
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I have noticed that fuel has a lot to do with it.Right after a fill up,things seem smoother and peppier.Give it a day or so and its right back to normal.Also the weather/temp/humidity seems to make a difference as well.
My car goes faster, and handles better after I've washed it and waxed it. Strangely the more cleaning and detailing I do, the better it performs. These animals are strange, majestic beasts that we can only begin to understand.
There will be some variation from day to day. Cool air, high air pressure, and low humidity can help the engine make power. Hot air, low air pressure, and high humidity can bog it down. Cars with forced induction (especially turbochargers) are more sensitive to heat but less sensitive to air pressure. Big swings in these conditions can trip up your engine's computer from day to day, perhaps causing slight differences in power, response, NVH, etc. There may be slight variations in fuel quality that may affect how your engine runs. Temperature can also affect your tires and suspension (depending on the tires and suspension in question), which may affect road noise and ride quality. At the same time, there are a lot of human factors as well. Your subjective opinions of things like vibration, handling, power, ride quality, etc. can change according to how you're thinking and feeling, even from moment to moment. This is why there is so much mistrust of the "butt dyno." So, in short: If your car feels different from day to day, it's entirely possible that something about it really has changed. It's also possible that something about YOU really has changed, even if that something is subtle and subconscious. As always, if you suspect that something is different, look for an objective way to figure it out, and go from there.
Temperature/Altitude/Humidity makes a huge difference. In my Lincoln, in the winter, I ran a 14.1 1/4 mile in ~40 degree temps, at (I think) below sea level Atco. This past summer, I hit the track (Island dragway) on the hottest day of the year...was still 90 degrees after the sun set around 9 pm. I couldn't go faster than 14.8.
In Minnesota at the current time I do feel my car respond different from day to day because at the moment it is 30 degrees and 50% humidity here, but yesterday it was 50 degrees, and 20% humidity, the huge change in temp, humidity, and elevation can cause you to notice a difference. Some of the posters seem a bit sarcastic, but you can tell a difference in a N/A car driven in Arizona, then shipped and driven in Washington.
Remember gas from an UST is earth temp, 55-60'F. This will matter in the summer, until your tank warms up to ambient. If you have a return fuel system this won't take long as it heat soaks from the engine compartment. My first car the struts were shot but I didn't realize it. They stiffened up when it was -10'F and I liked how it rode then. LOL
Yes - some days are flat, some peppy. Who knows? A sensor may read a bit differently, or the short term fuel and timing trims are better/worse.
Originally Posted By: Stanley Rockafeller
My car goes faster, and handles better after I've washed it and waxed it. Strangely the more cleaning and detailing I do, the better it performs. These animals are strange, majestic beasts that we can only begin to understand.
I've noticed that too. I just have no idea why. My car is like a mirror of myself - the better I treat it, the better it does.
i think for me i notice the biggest difference with a fresh fill up of gas. oh yeah and winter fuel is coming or it already came. bummer
I'm convinced that OBD1 cars are less susceptible to this. Fewer sensors and components, simpler fuel maps. I will agree that certain days my car feels a tad slower or less responsive, though I know my butt dyno isn't very reliable. Fuel maps are not perfect so there are always some situations where it'll be running a bit lean and feel sluggish. My father always said that any sort of power loss/gain over 5% isn't easily detected.
My ford truck runs good maybe 2x per month. I noticed better lubricants provide more consistent operation. MAy be due to good ring stack cleanliness and lube. The only truly GREAT synthetic oil I've run in the past few years is the Subaru Idemistsu Oil. Nothing in a Mobil syn seems to compare on butt dyno and for low odd-harmonic mechanical racket. Fuel quality is terrible but the latest mobil formulation appear to be the best out there yet.. Good they improved, it ws abysmal for a few years up at our port. If you have some water soaked ethanol in the bottom of your tank you get all kinds of consistency problems. The car would run BAD right after a gassup and then possibly better the next morning.
Not my Cruze. That car has a personality. It's definitely a "he" car since sometimes it works wonderfully, then other days with identical conditions it doesn't work as nicely. How the gearbox shifts, how the engine pulls the car up a hill, those things can vary day to day. The Honda does get the winter blues where it gets balky in starting (is getting a new battery soon), and lights up all the indicators on the dash when trying to have fun in the snow.
Check all your fluids (power steering, etc....) smile Could be related to that perhaps? But yes, I've noticed a difference in the weather, how my car drives. the first "cold front" hits (this past week) and the first start of the day, my car is kind of sluggish, so I kind of "baby it" the first mile and a half, to the on ramp, then it's 70+ MPH from there, for about 10 minutes :P
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