Need Advice on 2008 Kia Rondo
 

Being recently divorced and down to one income, any place where I can save money is paramount. I'm not financially desperate; I can stay within budget most months and save a little, but more is better.

One place I was naturally looking at in terms of savings was fuel economy. I drive a 2008 Kia Rondo with 60,000 miles on it. It's the standard Rondo with the 2.4L 4-cylinder engine in it. I do mixed driving, averaging around 40% city, 40% highway, and 20% suburban/exurban, but not quite rural. Call it "mixed" driving for short. Combined EPA rating on this model is about 22 mpg, and I'm getting around 22-23 mpg; call it 22.5 mpg as a solid estimate.

Recently, I started adopted some (not all) hypermiling techniques to save fuel. Call it "supermiling" or "hypermiling-lite". Here are the main modifications I did to my driving:

1. No EOC, but I have lengthened--considerably--my coasting distance to stop signs and traffic lights, particularly when I sense a "stale green" light.

2. My local freeways here in NE Ohio--I-77 and US-30--range from 55-65 mph speed limits. I go at the speed limits, neither above nor below. I'm hesitant to drop below the speed limits given traffic flow (again, half-hearted hypermiling), but I noticed before I was consistently going 60-65 mph in the 55mph zones and 70 mph in the 65mph zones.

3. It took a while, but I think I got the hang of keeping the tach constant going uphill (this is NE Ohio, mind you, not West Virginia), preventing downshifting into gas-guzzling gears on most occasions.

4. I did away with quick acceleration altogether. I kept the tach at 2,200 rpm or lower in all gears whenever possible. It seemed going 2,300 rpm or above when upshifting gave me "empty" acceleration when switching gears.


Here's a list of things I *didn't* do:

1. I did not do anything to the tire pressures. 35 psi is recommended (44 psi max. sidewall), and the tires ranged from 33-36 psi during my last fillup.

2. The original Kia roof rack, cross-beams and all, is still on the vehicle.


The results? Again, 22.5 mpg has been a consistent, solid average. I had yet to hit 24 mpg, let alone breach it...

...until now. My last fill-up, with these techniques employed, yielded 26.3 mpg--a 17% boost in mileage! Now I know a lot of folks on this forum can do better, but I'm pretty happy with the results. At my current pace, I'll be driving 15,000 miles/year. The difference in fuel economy would result in nearly 100 fewer annual gallons. If gas averages $2.50/gal, that's $250/yr savings. Furthermore, I can't help but think it'll add several thousand--maybe tens of thousands--of miles between brake replacements...

...but SOMETHING tells me I could do substantially more. And that's where I need the friendly advice of those on this forum. In short, I was wondering what your thoughts are on the following:

1. Is my acceleration from a stop about where it needs to be, higher (to get through the lower gears quicker), or lower?

2. Would I get an appreciable boost in fuel economy with more pressure in the tires? I'm not keen on putting 50 psi in the tires, but what if I keep them all, say, in the 38-40 psi range?

3. Would I get an appreciable boost by removing the OEM roof rack assembly?

Thanks in advance,
Phil

Welcome to the site ISV-2K8Rondo! Congrats on the better mileage.

1) Your acceleration is probably fine. To be honest, acceleration rate doesn't have a huge effect on fuel economy from my experience. Accelerating or not having to accelerate is a MUCH larger factor.

2) I would recommend pumping up the tires a bit more. Start with 40. If that works and you're comfortable with a little more go for it. Pay attention to the change in handling so you know how its changed.

3) Its probably not too hard to remove the cross bars of the rack. That will be your biggest gain. The rails you might have a lot more work into and they won't do as much.

Thanks for the feedback. On my second tank with coasting to lights and DWL. Tire pressure bumped up to 40 psi. Didn't notice much difference in how the car handles, though it seems to coast a little further to lights. Fuel economy for this tank on its way to similar reading as last tank (~26 mpg). I've used the A/C more for this tank because it's been unusually hot for September here in NE Ohio.

Taking the crossbeams off the roof rack looks pretty involved. Basically, it looks like I have to take the whole assembly off.

--Phil

Welcome Phil!

Since you do 40% of your driving in the city, a gain would come from timing lights and reducing the number of stops. Conserve that momentum!

Have you considered a ScanGauge or other instrumentation? That will really open your eyes and mind when you see all your data in real time. For many here at Ecomodder, it is their #1 modification.

Removing all the dead weight possible would also be appropriated. If you don't have an use for that roof rack, let it go, as it's not just dead weight but also increases the drag (though this effect is more noticeable in highway).

Got my second tank after "adjusting the nut behind the wheel" and bumping tire inflation up to 40 psi (35 psi recommended, 44 psi max. sidewall). Result was 26.9 mpg. I had to use the A/C much of the time as it's been unusually hot here in Ohio for September.

This tank will have less A/C use for sure. It's cool enough in the mornings to just use the vent. Which begs a question--what's the impact of using vent vs. using A/C, and how much does the temperature setting of the A/C affect fuel economy?

I've taken all extraneous items out of the Rondo, but it wasn't much; maybe 20 lbs. total. What I haven't taken out is the (a) the spare tire and (b) the roof rack, though I did get a can of Fix-A-Flat. I figure I'm saving more than enough gas in a year to justify my AAA membership if I need the car to be towed, anyway. The spare tire and the roof rack combined would, I think, yield FAR more weight reduction than 20 lbs.

Problem with the roof rack is that I simply can't take the cross beams off. I more or less have to remove the OEM roof rack as one unit. I know how to do that; it's plugging the holes I'm not crazy about.

What kind of mileage boost would I be looking at if I removed the entire assembly? Like 1% or 2%?

--Phil

The best way to use A/C is put the temperature control on full cold. Then, turn your fan on the lowest speed setting to stay comfortable. However, the fuel economy hit can still be pretty drastic. Some reports say up to 30%. I find it much lower in my experience, but I use it very minimally.

I probably wouldn't bother with the roof rack if you can't remove it easily. Instead, do a grill block, air dam or both. The gains will probably be greater anyways, and easier to do.

Keep your interior fan speed near high when its hot and you need AC. If you have a button to turn on the AC you can turn it on as you are coasting down hill or slowing for a traffic light like a jake brake. When you turn off the AC the fan will still blow cool air for a while after. I've been very satisfied with the ride quality with my stock tires aired up to 50psi. The max is listed at 44. Other tires would be too harsh and these tires are only a year or two old. I wouldn't recommend this on old tires but there is benefits beyond 55 psi if you're willing. Tire pressure and AC use where some of the biggest helps when paired with what you're doing already.

Also, set the A/C on "max" or "recirculate". Then you won't be dumping cooled air outside your car. And if you can can control the compressor; turn it on until it's cool enough (preferably when going downhill or decelerating); and leave it off until you're uncomfortable.

When I use the A/C in the city, my mileage goes from 62-65 down to 45-49. So it's 20-30% for me depending on lights.