rev up your engines, today I'm gonna explain, why cars get worst gas mileage as
they age and what you can do to minimize that gas mileage loss as your car ages
as an example, here's my 25 year old Toyota Celica, it was originally rated at
29 miles per gallon highway and now it still gets 28 miles a gallon, which isn't
bad considering it's got two hundred and thirty-nine thousand miles on it, now I
can't directly tell you the efficiency of this car, because it's so old it's obd one
it doesn't have all that fancy new data I can get on later my car, so I'll show
you a couple other cars where you can actually see how efficient the car is as
its aging, take this 2004 Honda Civic, it's ten years newer, so I can use this
to get some serious data, and I'm using this new tool that I got, it's a launch
X431 pro mini, it's hooked up Wireless to the OBD connector and we're gonna see
how efficient this engine is running, all cars are different, this does them all and
as you can see down here, the AF LAMBDA which is the air fuel ratio, is going
between a perfect one point zero zero and point nine nine, that means that this
Honda is almost running perfectly, one point zero zero is perfect and point
nine nine is really close, so even though this car is twelve years old, it's still
running almost perfectly, now that's a new customer's car that I've never worked on
before, so I don't know the gas mileage, but on my wife's old 07 matrix here
that's 12 years old, I know what the gas mileage is, it was originally rated at 36
miles per gallon on the highway and guess what, it still gets 36 miles a gallon on
the highway, so if you got a vehicle that's running at 99 to a hundred
percent efficiency, hey it's going to get pretty much the
same gas mileage, and here are the key to getting good gas mileage is twofold, one
you want to buy a well-made car, hey this thing with 239,000 miles still gets 28
miles a gallon instead of the original 29, so number one you got to buy a
well-made car, but then of course you have to maintain the car, so that the gas
mileage doesn't drop dramatically as the car
ages, now the reason cars get worse gas mileage as they age is
basically wear and tear, as you're driving the engine, the piston rings have
to seal the Pistons, but if you don't change the oil enough, gets too much dirt
it wears the piston rings, they don't seal right, and voila
there goes your efficient engine, and lets say you never change your fuel filter, if
it gets clogged up the fuel pressure is gonna go down, it's gonna run poorly
because the computer will keep trying to compensate for it, and it'll get worse
gas mileage, and realize that these filters aren't 100% efficient, things can get
by them and if they do get by them, they can damage your fuel injectors, they can
clog them up yes, but if you get little pieces, they can actually wear them out
like sandpaper, then they spray wrong, look at all these
tiny little holes, that's the spraying end of the injector
if they get clogged or if they get damaged, then it sprays like a bad
showerhead all over the place and your gas mileage will have to go right down the
toilet, now in the olden days when cars had carburetors like this big
four-barrel carburetor, these are mechanical they just flat wear out and
when it wear out you get really bad gas mileage, and then you either rebuild it or
you throw away and put in a brand new carburetor, but these fuel injectors are
much more efficient and if well made can last a really long time, that Celica of mine
still has the original fuel injectors on it, two hundred and forty thousand
miles and they're still spraying strong, so as long as you keep them clean, use
good fuel, keep your fuel filter clean, they can keep you getting good gas
mileage for a long time, now of course you want to keep your air filter clean
because if your air filters dirty, you're not gonna be able to suck enough air in
and the car is gonna get worse gas mileage, and in many modern cars they use
what are called MAF sensors, mass airflow sensors, if these get dirty and all of a
sudden you get bad gas mileage, sometimes it's as simple it's just cleaning these
things, see these tiny little wires just resistors on them, if you clean them with
some mass airflow sensor, a lot of times the car will go back to getting good gas
mileage, just to make sure you use mass airflow sensor cleaner
it's very particular, I've got a whole video on that called make your car run
better with a little spray cleaner, you can watch that and it shows how you can
clean it yourself, and if push comes to shove, you can always buy a new MAF
sensor, you get one of these scan tools hook it up, you can look at the data and
if it's really bad it'll trip a code for a bad mass air flow sensor
they just bolt on and off they're very easy to change, now another
reason as the car ages it can get worst gas mileage is the brakes, you want
to check them every once a while to make sure they're not dragging, because if the
brakes are dragging, while you're driving down the road the brakes are gonna hold
the car back and you're gonna get worse gas mileage, I even had one customer
years ago the BMW complaining he was getting horrible gas mileage, so I said
let's go for a ride, and we went for a ride and it turned out
that he drove with one foot on a gas and one foot touching the brake, because he said
oh they taught him how to drive that way in driving instruction school, I got out
of the car later I watched him drive down the road and sure enough he's
driving on the road and his brake lights on the whole time, you know whether
you're stepping on it yourself or they're dragging, you're gonna get bad
gas mileage if your brakes are dragging, and the last thing I'll talk about in
aging and bad gas mileage is your automatic transmission, if your automatic
transmission isn't shifting right, hey you're gonna get worst gas mileage, if it
stays in the lower gears longer or maybe doesn't even shift into overdrive
there goes your gas mileage and the same goes for dirty transmission fluid
automatic transmissions drive through the fluid dynamics and if you got old
dirty fluid with a lot of friction in it, guess what you're gonna get worse gas
mileage because it has more friction in the engine and friction takes
energy up, but as I said, if you maintain your car correctly, you might get one that's
got 240,000 miles on it and it's still getting almost the same gas
mileage it did when it was new, and as I said the main ways to achieve that is to
one, buy the correct car and two, maintain it so it doesn't wear out unnecessarily, so
if you never want to miss another one of my new car repair videos, remember to
ring that Bell!