How unusual do you find it for a 1996 4-cylinder GMC Sonoma to get a horrible 18 MPG?

Question

I thought this thing was supposed to get 30 MPG on the highway and a good 23 MPG for the streets. Anyway I slice the cheesecake pie, city or just albout all highway driving, I get a terrible 17-19 MPG with it.

It's not right, I'm supposed to be doing better than that.

IT'S A 4-CYLINDER WITH 120 HP, FOR CRYING OUT LOUD!

Answer 1

What are your driving habits?? Are you carrying any extra weight? Do you run the A/C all the time? Correct air pressure in your tires? All these together will lower your MPG. There could be engine/tranny problems too. Take it to a shop and have all your sensor data read and compaired to the specs found in the GM service manual. Things like a coolant sensor, oxygen sensor, MAP sensor or MAF sensor giving erroneous values to the computer can cause less MPG. Also the TCC or OD in the tranny not engaging can cause it too.

Answer 2

Where did you get that 30 mpg figure? In real life 18 mpg isn't bad, even for a four cylinder, in a mid sized SUV. It has to do with how efficient your engine is running. Some engines just won't get excellent mileage no matter what you do. If an engine is not designed especially for high mpg, then it isn't going to get it. Your engine needs X amount of gas to get 120 hp, while another engine only needs 1/2X to get the same hp. GMC 4 cyl engines HAVE NEVER BEEN KNOWN FOR THEIR FUEL ECONOMY,FOR CRYING OUT LOUD.

Answer 3

If you live in california, it's cuz of the fuel there. While trying to get cleaner fuel, they dropped the MPG. My inlaws drive a honda pilot. In Calif, the get 17 mpg. If they fuel up here in Idaho, they get 20. If you live somewhere else, try the usual suspects. #1, put in a Katadyne type high flow air cleaner. Good for 1-3 mpg improvement. And it last for a million miles with regular cleaning. #2, a complete katadyne air intake system (around $300) will get you 3-5 more mpg but it takes a while to earn back the cost of the part. #3, if you have many miles on the vehicle, check the exhaust system. Cat. converters break down around 12000 miles and can clog exhausts. On the same line, a high flow exhaust system, while expensive, will also boost those MPG's. After that, keep it tuned, and under inflated tires rob MPG's too

Answer 4

My 90 HP,1650 lb,1/2 ton truck-(w/auto trans) always averaged 18mpg. in city driving. Out on the highway at 65 mph-unloaded,one occupant,tailgate down,no a.c. on ,no wind and the engine at 3200 rpm would deliver a sound 29 mpg. Sticker ratings have little to do with real world actual mileage. If you pussy-foot it through 1 tank of gas-(empty load) you may be surprised.If your check engine light does'nt work then-you're engine is running in limp-home mode.This mode is the worst of all for fuel efficiency,thus the poor mpg at easy highway speeds.