Best mpg sofar, but driving fast !?

[McPatrick]

A week and half I got the new Kumho LRR tires on in size 155/80 R13 and I couldn't wait getting the first results in. Frankly I was hoping it would improve my base line of around 50 mpg with 10 percent, shooting for 55 mpg.
I had a trip within Ohio and straight up to Michigan from there, totalling 350 miles. Enough for a pretty good reading even when calculating by tank fill ups I figured. So after 350 miles of doing between 60 and 65 mph (which I find not very easy to do) my heart was beating a bit faster when gassing up. Only to end up with disappointment as I could get 7 gallons in there, meaning I did 50 mpg again! I was pretty bummed that the LRR hadn't done the slightest thing.

So when I drove back last night I didn't feel like driving slow, also because my two year old was in the back constantly asking for 'mama' with still thre hours of driving ahead, so I drove 77 mph in Michigan and 72 mph in Ohio.

Coming home I filled up at the gas station around the corner, which is after 225 miles and what do you know: I had driven 54.5 mpg!

So I was stumped. is my VX more efficient at higher speeds that at say 62 mph? I do know that when I drive 62 mph the VTEC never kicks in. When I go 72 mph it kicks in frequently and when it does the speed goes up and I have to be easier on the gas pedal to remain at the same speed.

I haven't used any hypermiling techniques yet because I wanted to see the effect of the LRR.

Anyways, do you think the VX is better on gas at 72 than at 62 mph? Or was this just due to the fact that you cannot calculate very good going by tanks of gas (even while driving pretty good distances)?

[cmhj2000]

Which model Kumho are you using?
TIA

[McPatrick]

Well i have another trip up to Michigan this weekend (and back) so there is another 450 miles right there. And I think I will start by driving faster again

I put Kumho Touring 795 A/S on there in 155/80 R13.

You can see my VX with these tires on them in this thread: http://www.gassavers.org/showthread.php?t=3993

[MnFocus]

In the context of keeping things consistant ...follow the same routes at the same speeds . You'll never know if it was the speed or the roads/traffic or the direction/time of day or if the driver is that good if you change up on the test . my 2¢

[McPatrick]

The trip is so easy that I don't even have to be a good driver (which of course I am ). Traffic isn't bad at all. I could put a cruise control on if I had it and hardly ever would have to turn it of to change speeds. I will drive 72/77 mph again on the trip up and gas up and then drive 62 mph on the drive down and gas up again. Pretty curious how that will turn out.
The LRR are defiately working though because the best I got before was just over 50 mpg (like 50.2 or so).

After I know for sure what a base line is with these tires I am gonna put cardboard over the grill and rear wheels to test that out.

[Guillermo]

What tire pressures do you use?

[McPatrick]

The tire wall says 35 psi, but I use 40 psi.

[Sigifrith]

Originally Posted by McPatrick

The tire wall says 35 psi, but I use 40 psi.

Time to go to 50PSI.

[McPatrick]

Think the tires can handle that?

[91CavGT]

I used to own a 1991 Cavalier with a few modifications done to it (no aero mods). If I drove the speed limit (65 - 70 mph) then the car would get 35-38 mpg consistently. However I was in a hurry one time so I drove at 80 mph and got 45 mpg!! I repeated driving at 80 mph on different roads to see if it was a fluke, but I still got 45 mpg!

I guess in some cars, the advantage of the higher revs equal to better gas mileage because the engine is not struggling as much.

[Sigifrith]

Originally Posted by McPatrick

Think the tires can handle that?

Look up krousdb's posts. He ran both a Del Sol, & VX with very high tire pressures. I'm running 50 in my VX with no problems so far.

[McPatrick]

Well, 50 psi it is then. I'll pump them up tomorrow...

[Stevo440]

I've been runnin 50psi/45psi f/r in my Kumho 795 A/S tires 175/70/13's on my CX for 38,000 miles with no problems, and they handle sooo much better then when I tried 32 and 35psi. With 0 toein on my alignment they seem to be lastin forever. The ride is alittle harsher but not much with the 50psi. The steering is alot easier almost like havin PS.

[omgwtfbyobbq]

Originally Posted by 91CavGT

I used to own a 1991 Cavalier with a few modifications done to it (no aero mods). If I drove the speed limit (65 - 70 mph) then the car would get 35-38 mpg consistently. However I was in a hurry one time so I drove at 80 mph and got 45 mpg!! I repeated driving at 80 mph on different roads to see if it was a fluke, but I still got 45 mpg!

I guess in some cars, the advantage of the higher revs equal to better gas mileage because the engine is not struggling as much.

Did you do loops to make sure nothing was throwing the test off?

[Hockey4mnhs]

cant wait to see the new results

[jcp123]

For what it's worth, 70mph was the only speed my old conversion van would average 16mpg or above, despite its bricklike "aerodynamics", if they can really be called such...

My best tank in my Focus also came at 70mph. It's nearly identical to my normal cruising speed of 63mph, but since I'm getting somewhere faster, 70mph wins. 55 doesn't do much for my car, it's an MPG or two below 70 or 63.