First Hwy Run... Fuel Economy Report
 

Finally got around to doing a a highway drive that lasted just over an hour.

Conditions: Dry, temps in mid-70's / 4700 miles on ODO / Only mod is a K&N drop-in air filter and a spoiler for looks.

72 miles / ~60-65 minute drive -- both ways

Average MPG based on car computer
W/O A/C: 37.7
w/ A/C: 34.5

Mostly with cruise control on... leg #2 (w/ air on) had to deal with some traffic... a few roll-ons to 80'ish.

Notable: I really liked how the FRS -- while on flat sections in 6th gear @ about 3.1K on Tach... smoothly (and quickly) got up to 80'ish mph for dealing with traffic. Rig tracks nicely... love the sound coming out of the engine compartment.

As noted in numerous posts... the upper regions of RPM is the place to be... dang hard not to smile...

cool.

31,000 revs? either a typo or you did some magic.

I'm pretty sure he meant 3,100. You can use common sense for that. :bonk:

....or i can have a little fun...... dont be a party pooper

hahaha i love that cat

I recently did a 300 mile round trip all highway (only engine mod, Apexi drop-in), slightly higher speeds than OP 75-80mph w/ ac for the whole duration. I ended up with the same 34 mpg. I'm going on a limb and saying the speed matters less if you're able to keep a consistent rate of speed during the trip.

Honestly this was my one reason for justifying the purchase of a lightweight car (gas savings), it just happened to come in a sports car package with a few extra smiles, "mpg with style" eat that accord and elantra.

I average 38 doing 60mph.. the direct fuel injection does save gas. My first tank average was 32mpg

So using A/C does lower mpg? I thought that was a myth

^ He said that he did a few "roll ons" to 80 mph (which I assume to mean quick, brisk acceleration). On a trip as short as 72 miles (which is about two gallons of fuel, give or take), that may very well have accounted for the difference in fuel economy. That and how the pump at the station is set to shut off.

I'm pretty sure it does lower MPG. But i also think "they say" that it is more efficient at highway speed to be windows up/air on than windows down because of the increased drag.

I could be totally wrong, but I believe I got that from somewhere reliable some time ago, havent done my own research

Hello everyone, the decrease in MPG with a/c on is correct.

The reason this happens is because iof the added load on the engine .
When the a/c button is pressed the magnetic clutch is engaged to allod power flow from the engine to the compressor and ultimately moving the freeon .
The system a high and low pressure sensors that the a/c control modual monitors to determine if the system needs to be turned off or on. The system is turned off at WOT and when desired cabin temp is achived.
I feel tyota has built a very well designed system that is easy to use and maximizes mpg while not sacrificing performance.

I hope this helps.

A/C makes a difference but I don't think it would make that much a difference.

What isn't mentioned (or if it was I missed it) in the OP is whether or not both legs were on the same/similar terrain. That could also account for the difference.

If you go to my Owner's Journal I have all my mileage there documented by tankful. Looking through it I don't see a significant difference between winter months (no A/C) and summer months (A/C all the time).

June/July/August, I averaged 31.76MPG with all A/C all the time. Dec/Jan/Feb I averaged 32.58 with no A/C. 90% of my driving is done on the same roads at the same time of day in both occasions. There would have been a difference in fuel mix (summer vs winter blend).