Fuel milaeage

[Balidio]

I know that this is a pretty old thread, but I've also been recently dealing with really low fuel efficiency issues with the Pride I bought last month. What I've discovered are a couple factors here in the Philippines that adversely affect our car's fuel consumption. These are aside from the local driving/traffic conditions. First, and probably foremost, I've discovered by reading various maintenance/repair/service/shop manuals for the Aspires/Festivas/121s/323s (cars that use the Mazda B3 engines) that some engines of the same displacement (specifically the 1.3 Liter) were made with different compression ratios for different markets. I'm guessing this was done due to the varrying emissions requirements in the different areas. It seems like the North American and some European models had 9.7:1 instead of the 9.4:1 that we have here. Of course, the higher compression ration increases the power and therefore the fuel efficiency as well - major factor... Also, gasoline here is diluted with ethanol, I think about 10%. So that also increases the fuel consumption.

Can anybody out there confirm or deny my research?

[TominMO]

We get ethanol added to gas in the States in the winter. My observation is that it decreases mileage about 10%.

Of all the factors affecting fuel mileage, the most important is the space between the driver's ears, and his/her right foot. When testing my mostly stock Festy (except 13" tires up front), I drive a loop around the city at a consistent speed, usually 60 mph. That consistency gives greater mileage than "normal" driving. My car's best at 60 is 52.0 MPG; at 55 the car got 58.5 MPG; at 45 it got 62.5 MPG. In purely city driving below 45 MPH, using hypermiling techniques, it got 50.5 MPG. This is all on summer gas, by the way.

[drddan]

Did 2 mileage runs(officially unofficial) with my Festiva:
1) with stock 12" tires, 200 mile check with 150 hwy and 50 city. Got 36MPG
2) with 14" 195/60/R14 tires and about same mileage conditions and have dropped to 33MPG Carbed, think its need tune up as sounding like its bogging and the larger tires seem to have caused some power loss so I think my right foot has grown HEAVIER!
All runs included 70 MPH hwy. If I could go 50 MPH, i'm sure I would see 40 MPG.

[batstiva]

^^ The flip side is your speedo and odometer are going to read slightly off due to the different tire size. For your consideration.

http://www.miata.net/garage/tirecalcold.html

FWIW, you are running the same tire setup as I had with my RX7 wheels, and I think my speedo and odometer were off by about 6 percent. What your vehicle uses for calculation has not changed, but the outside dimension of the tire is larger, ergo you actually travel farther with each wheel revolution than your odo is going to show. So you are actually going farther faster than it appears by your gauges.


Our gas here has up to 10 percent ethanol in the winter, less in the summer, but we don't actually get pure gasoline anymore.

[drddan]

Doing 60 on my speedo, i'm actually doing 64mph. So I guess my numbers with the bigger tires dont mean anything unless I get out the math book and compensate for the tires.

[batstiva]

Doing 60 on my speedo, i'm actually doing 64mph. So I guess my numbers with the bigger tires dont mean anything unless I get out the math book and compensate for the tires.

Kind of what I was getting at. When I switched to the tires you are running now, my commute magically got shorter (according to my odo).

[drddan]

That would explain the 320 miles to a tank. It was 360.

[MAVRICK513]

Back in the early 90's my friend & I drove my 4 spd manual trans carbureted '89 (with 60,000 miles on it) on an 8 hour Summer trip down south using the A/C all the way and got 45 mpg. I don't take it that far anymore. Now that I have a family I currently only use the car to drive to work 8 miles each way. The car has 147,000 miles on it and with 10% alcohol in the gas I get 30.5 MPG. I believe it would still get 37-40 on a nice long trip. We also have a fuel injected automatic '93 with 136,000 miles on it that gets about the same gas mileage. Alcohol definitely does cut down on the mpg. I have been told that if you convert a car to alcohol, you will go through twice as much alcohol as you did gas to go the same distance.