Strange increase in mpg w 2011 Sonata

Been driving my 2011 Sonata w 4900 miles on it for a year. Been using Shell regular gas & getting 26.5 mpg avg. 2 wks ago I filled up w the mid value
gas by mistake. Now I'm getting 29.5 mpg! with the exact same driving habits.
An increase of mpg like that makes the mid value gas cheaper to use! Anybody else have this same experience?
TIA Scotty
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ichnee wrote:

How are you calculating the mpg? It would take several takes to get an average.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Last time I went to my independent mechanic ( been going to him for years with no issues) he advised against using a certain brand diesel. Says he wouldnt put the other big brand in his 4WD. Maybe he,s got shares in one??????

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Paul in Houston TX wrote:

Yes, that is one possibility as it takes generally at least 5 consecutive tanks to get a good average. Another is the change from winter to summer gas formulation. A third is that maybe the mid value gas is some of the rare gas that hasn't yet been poisoned with ethanol.
Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Ichnee" ha scritto nel messaggio

With all the hyundais I drove, the mileage was better after 10.000 Km (about 6000 miles), so, probably the reason for increase is just this, and not the fuel.
Another slight improvement in mileage I noticed was changing oil and using on my Sonata a good quality 5W20 instead of 5W40 I had before; but some people say that 5w40 oil gives a better protection to engine in hard driving conditions.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Some of the change could be the seasonal formulation. I get at least 2 mpg better in summer than winter. It improved about a month ago and will decline again about November. It is possible the mid grade has less ethanol to start with, thus the better mileage. The efficiency also improves after a few thousand miles on the car.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 5/10/2011 12:56 pm, Ed Pawlowski wrote:

I think it has less to do with the gas, and more to do with outside air temperature.
If you know much about the tuner culture, one of their favorite modifications for increasing power is to install a cold-air intake. This pulls air from way down near the pavement, where it is cooler, rather than from an inch or two under the hood.
I've noticed the same thing in my Sonata -- better mpg in the summer than the winter. I think the colder air of winter allows the engine to produce more power at the expense of mpg, while warmer summer air can't produce as much power without knocking.
--
Larry Harvilla
e-mail: larry AT phatpage DOT org
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I havent had this exact experience, but, I started going to this gas station that has some additive in the gasoline, and I consistently get another 3 mpg (versus all other brands) for the same type of driving each and every week. I think its a Union 76 gas station.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks to all for the great advice.
The 26.5 mpg avg is based on 12 full tank fillups. It also agrees exactly with the 'overall' mpg averge on the odometer. The 29.5 mpg comes from the 'current' milage on the odometer.
Seasonal gas formulation and 'engine break in' sounds like the real answer. Won't know for sure till my next fillup.
Ichnee
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.