2006 Sonata GL 5-speed stick fuel mileage

Well, I've got three tanks under my belt now and the results are 27, 29
and 27 again. This is for 70-80% highway driving and 20-30% city, if
you call the towns I drive through cities (I live in rural northcentral
PA). My cruising speeds have been 55-60.

Still too soon to make a call on average mileage, but I admit to being a
little disappointed. My 1996 Plymouth Grand Voyager with the
3.3L/4-speed automatic was getting 22 MPG in the same driving regime. I
thought the much smaller Sonata with a much smaller engine and stick
shift would easily get 30. Not yet...


Matt

 

Don't worry. You'll break 30 MPG after the engine completely breaks in.
I'm just over 5,000 miles now with mine and I see the mileage slowly
increasing. Most claims I have heard is that it can take to the 10,000
mile mark these days to achieve peak mileage.

This weekend coming, or maybe next, I will be doing my second oil change.
Finally will be putting in Mobil One synthetic 5W-20. I am hoping to see
an increase on mileage soon after.

 

Do you have a few of your mileages along the way to show the
progression? I'm curious to see the curve.

I've used synthetic for 25 years, but never say enough of a mileage
difference to even say so. And I compute the gas mileage on every tank
of gas I run through all of my vehicles and record it in a log in each
vehicle. I've got 20+ years of data.

Lots of other good reasons to use synthetics, but fuel mileage isn't one
of them ... Amsoils wild claims notwithstanding.

Matt

 

As you probably expect, the gains are largest initially and become
smaller as the engine breaks in. My '04 Elantra's mileage started out at
27 and this past summer, I hit 37 on the highway. I doubt that you'll
see that with a bigger car and a bigger engine, but you should see a
significant gain over time.

I switched to sythetics in both the engine and the transmission.
Although the summer gains were small (1-2 mpg), I don't lose as much in
the winter as in other cars I've owned that I used natural oils in.

 

I lost track in all of the earlier conversations Brian - what synthetics did
you switch over to? Both for the tranny and for engine oil. What filters
are you using for the engine now?

 

The transmission requires a GL-4 lubricant and I'm using Redline MT-90.
There was a recent TSB from Hyundai suggesting a thinner lubricant than
the originally recommended 75W-90, so Redline MTL may work, too. The key
is that you MUST use a GL-4 lube, as it's necessary for proper
synchronizer operation. Amsoil also makes one and I think Royal Purple
does, too.

In the engine, I just use whatever full synthetic 5W-30 oil that I can
find on sale. For a while, Walmart was selling their full synthetic
5W-30 Super Tech oil in 5 quart jugs for ~$12, but I haven't seen it in
over a year. Once I use up what I have on-hand, I'll probably end up
using Mobil One, since that's what's most commonly on sale around here.

BTW, I did some research on the Walmart oil before buying it. It's a
full synthetic (not a blend) that's produced for them by a
well-respected oil blender that blends motor oils for many of the brand
names you see on the shelves. Analysis reports show it to be equivalent
to other synthetic oils in terms of viscosity, additives, etc.

I've been using Purolator Pure One filters. The part number is PL14459.
I had been using the slightly larger PL24458 (for a bit of extra
filter/oil capacity), but they discontinued it this past summer.
Purolator filters meet the OEM filter specs for proper bypass valve
pressure and have a filter medium that's at least as good.

Stay away from Fram filters; they're junk and they can cause problems
with Hyundai engines. There is a TSB out about that as well, though
Hyundai doesn't specifically name Fram filters as the problem, probably
for fear of being sued.

 

I also don't think, in the long run, you will be disappointed.

Remember also though that, beyond the fact that you are still in break-in,
you are also still in January. I have a couple of vehicles that are easily
over 30 mpg in the Summertime. But in Winter they max out at 27.

Another factor: Usually, we run our defrosters a lot, especially if we have
to drive at night. Even the "high-low" setting is also a defrost setting,
and any defrost setting runs the compressor. The compressor seems to take
an even bigger bite out of mileage in Winter than it usually does.

I do still wonder, especially with the close EPA numbers, whether a 4 with
an automatic will end up doing as well or even slightly better than your
manual, especially on the highway.

But I hope you enjoy it.

Green Valley Giant

 

I'll never know as I'm not going to buy a second Sonata!

So far, it isn't a bad car. Part of my problem was getting spoiled by
my Chrysler minivans. Even though they are a little larger than I like,
they are extremely comfortable to drive, quiet, handle resonably well,
have great HVAC, controls, etc.

The Sonata is a nice car, but it has a few quirks that I wasn't able to
catch on a test drive.


Matt

 

That's why I installed a switch in my Elantra that allows me to manually
control the A/C compressor. I keep it turned off unless I specifically
want it for cooling or defogging. '01 -'03 Elantras can be modified to
allow the A/C switch to control the compressor independently by simply
cutting one wire, but the control module in newer cars is different.
Canadian cars have independent compressor control standard.

Not likely. From what I've seen, Hyundai automatics struggle to get
close to their EPA ratings, but their manual transmission cars can
readily exceed them.