Worst gas mileage ever!

I have a 97 RAV4. I was told the gas mileage was 25 Hwy when I bought it last year, used. I am on a road trip right now and I think the gas mileage is even worse than ever. I took several road trips over the summer (used air conditioner the whole way) and the mileage is worse now (no AC used, no heat, no open windows). I go about 70 - 80 on the highway, consistently. Looks like Im getting 20 Miles to the gallon if Im lucky on the freeway. Bad. I can actually watch the needle move on the gas guage.

I recently found out I have a faulty O2 sensor. It is sluggish and will need to be replaced when I smog the car next year. I also just got a tune up with new spark plugs, air filter, oil change. I also just got four new tires in the past month. The tread is not too heavy on them (they are not snow tires or super chunky).

What do you think might be contributing and/or can help??

Pushing that shoe-box down the road at 80MPH takes a lot of gasoline…

How did you find out you have a “sluggish” O2 sensor??

Some tires roll easier than others. Since you changed tires recently the new ones may require more energy to roll along than the old ones.

Not all road trips are equal. If you are traveling on a windy day and the winds are headwinds that can kill mileage. If you are going 80 into a stiff wind you’ll get horrible mileage. More hills on a trip can eat up gas too.

The bad 02 sensor won’t help. Why are you waiting to replace it? If mpg is important to you then do it now, or don’t fret over mpg.

Aa stated by Caddyman you are driving a poor car for aerodynamic effects. You are pushing a lot of air and the energy you need to drive the car at 80 vs 65 mph is exponentially higher. Going just a little faster burns up much more gas. Driving at 80 mph and concern about gas mileage are inconsistent. If you want to go fast you pay the price in burning more gas to do it.

If the O2 sensor is bad…it could cause part of the bad gas mileage. One of the biggest reasons is how fast you drive. Reduce your speed to 60 will have a big effect on gas mileage…also how fast you accelerate is a factor…jack-rabbit starts is a killer on gas mileage.

The “I was told” part seems a little fishy to me. Were you keeping track of your mileage before the drop? If you go over to www.fueleconomy.gov you can see what the EPA rating is on it and keep in mind that the highway rating is more for 60-65 mph speeds, so I would not be surprised if you got down to 20 driving faster.

Keep in mind that wind resistance is an exponential function of your speed and this is not the most aerodynamic nor the most powerful vehicle out there, so running at 80 is probably pushing it pretty hard.

The faulty O2 sensor and the new tires are conspiring together to lower the fuel mileage.

You’re probably stuck with the tires, but I recommend having the O2 sensor replaced now instead of waiting until the smog test.

The check engine light goes on often and i have to have it switched off. My mechanic says its a sluggish O2 sensor. Its a part that is pricey - and doesnt seem to be affecting the car (maybe mileage), so I am waiting until I really need to replace it. I guess I gotta go slower, huh? Thanks!!

The AWD model is rated for 24 MPG highway, the 2WD 27. However “looks like I’m getting 20 MPG.” isn’t exactly confidence inspiring. You need measure fuel economy over at least 3 fill ups to determine what kind of mileage you’re actually getting. If you had bad O2 sensor it’s possible the car is running in closed loop mode at all times whenever the check engine light is on, this can cause a significant drop in mileage.

For what it’s worth, getting 20 MPG hardily qualifies as “worst gas mileage ever.” If my Bronco ever achieved that, I would be in contact with the Vatican ASAP.

I also have a 97 rav; it is a 4 cylinder and front wheel drive. I drive conservatively to save gas and keep my rig well maintained. The tires are factory spec size.

Over the last 3 years, here is what my mpg averages:
Summer: 32 mpg
Winter: 28 mpg
Overall, right around 30 mpg

Not sure how your rav is set up, re 6 or 4 cylinders, front/4wheel drive but you should be able to do better on your mpg.

Check out rav4world.com for some help

It’s cheaper than the catalytic converter that you are slowing destroying because of the bad O2 sensor. The O2 sensor is also a factor in your gas mileage. Latter, the plugged converter will be a factor too.

thank you! Wow, my car is really far from that… thanks for the information. I’ll def. check out that website. I have a 4 cylinder, 4 door and front wheel drive as well. I also have factory spec sized tires.

Yes, but you are driving TOO FAST for someone who is concerned with mazimizing her gas mileage.

When the speed factor is coupled with a defective O2 sensor, that explains about 90% of the drop in gas mileage. Even if you think that you can’t afford a new O2 sensor right now, you need to realize that the extra cost of gasoline is draining your wallet every time that you fill the tank.

Replace the O2 sensor, slow down, and be sure that your tires are inflated properly, and you will save money in the long run.