: 1999 Catera gas Mileage

11-03-12, 08:56 AM
I just got a 99 Catera but I don't think I am getting the kind of mileage that I should be getting. I get about a 100 klms/62 miles per 1/4 tank of gas. Does anyone know if this is about right for this car or should I be getting more than that.


11-03-12, 12:18 PM
It's hard to do a mileage check on a 1/4 tank of gas. All tanks are shaped differently, so the top 1/4 will be a different shape and a different size that the middle og the tank, and the bottom of the tank.

It's also hard to get a good number over 1 tank as there are different factors in how a car performs. Cold winter weather will give different numbers than if you were driving in the summer. One week you might do more traffic driving, or one week you might do more highway driving.

To do a proper fuel mileage check, write down your mileage, then fill the tank to when the pump shuts off and drive regularly. Over the next 2 or 3 tanks, keep a record of how much you put in and if possible, fill at the same station and use the same pump and always stop when the pump shuts off. Then write down your mileage and subtract the first # with the second, this is your mileage for the test. Do not put in more gas until you figure the mileage out. You start with a full tank and finish on an empty tank.

Now add up how much gas you used during the test and how many miles you put on the car. Divide the gallons into the mileage and this is your fuel mileage.


11-04-12, 11:06 AM
Yes, it is very hard, albeit impossible to guage gas mileage from 1/4 tank estimates!
As stated above, fill up at the same place, etc., etc.

Fuel mileage can also vary from trip to trip, & driver to driver.
I can drive our Cat on a 200+ mile trip (to my Daughters home), and get 27+ MPG.
When my wife drives it to work (one trip @22 mi. each way, another is 45 mi. each way) she gets around 24-25 MPG, and I know I drive more aggressively than her!

11-04-12, 05:45 PM
I can drive our Cat on a 200+ mile trip (to my Daughters home), and get 27+ MPG.

She must live 200 miles down hill from you. Or you is white, located in Florida, left turn signal always on, and don't go above 45 mph!

the best I ever got was about 23 mpg!

11-09-12, 01:53 PM
Well I've been able to figure out that I can go 100 klms or about 60 miles and it cost me $ 75.00 for gas. ( that's regular ) Something doesn't seem right to me. I was told to look at the air filter or what if I tried some injector cleaner in it. Any thought on that.


11-09-12, 03:44 PM
i live in USA. my 2000 sport with 152k can go up to 230 miles - city and 320 miles on highway per tank , im using premium 93 octane (by manual).
- new air filter,
- new fuel filter, fuel pressure tested - ok
- cleaned mass sensor and throttle body,
- use injector cleaner every 5k miles or so, did seafoam cleaning like 3 times already in 30k period
- personally removed injectors and run cleaner through them under pressure (just like shop do)
- spark plugs was replaced about 20k ago with original Bosch (by manual) and new 1,3,5 cylinder coil
- driving fast but not crazy, usually accelerating up to 3000rpm, keeping my trunk empty and monitoring my tire pressure
All this procedures and - 230miles/city and 320miles/highway per tank

- compression test was preformed on 11/5/12 - cylinder 1,2,4,5,6 showed 185psi to 195psi range; cylinder 3 showed 170psi fist time, then second time test showed 150psi.
Now i have two ideas:
- valves on 3rd cylinder not closing correctly and trowing fuel in exhaust
- injectors works on reach