OMG My Gas Mileage!!! General Question Need Everyones Help

[MZ-N10]

16mpg combined on stock 16s with a pv muffler.....

[18Foxtrot]

New, 21mpg with everything stock. Now, 19mpg with K&N air filter, Bridgestone AT Revo 265/70SR16 tires and Mobil1 oil, changed every 3000 miles. Everything else on the engine/transmission is still stock.

[Lizardmen3477]

so bigger my rims and tires are less gas im gonna get as well cause i wass gonna get some bigger rims soon? i had a complete maintence done to it few months back so i think all that stuff is good but about stuff to put on a car to make mileage better is that tornado any good or the bosch plus 4 spark plugs and minor stuff??

[johnnyapollo]

A short answer on those gizmos - don't bother, they don't work.

Some engines just aren't as efficient as others - plus environmental factors and general engine wear and tear all contribute to gas consumption. I usually get around 12-13 MPG on my VX in the city - it goes up to about 16-17 on interstate driving trips. The more performance mods you have, the worse this gets - mostly because the mods introduce higher airflow or more fuel boost - this creates better response times and usually causes the driver to drive more aggressively - it all contributes to poor gas mileage. Remember the VX weighs in excessive of 2 tons with a driver - the full ladder frame and full-time 4wheel drivetrain all has its toll on engine efficiency. If you're looking for a gas saver, buy a motorcycle and swap off driving every other day - the VX just isn't a good candidate for economy gas mileage.

-- John

[VehiGAZ]

A while back someone was complaining about getting very low mileage, but they were not calculating their mileage correctly. That person was filling up, driving until the needle is on E, then filling up again and dividing the 22 gal tank capacity (instead of how much gas they actually put it) by the miles on the trip odometer. This led to an overly low mileage estimate. Properly done, you should fill your tank until the pump shuts off, reset your odo, drive it to empty, fill it until the pump shuts off again, then divide the miles driven by the actual number of gallons you just put in.

Now, I'm not trying to say that you must be doing the math wrong, but 10 mpg is unusually low, so I suspect something is fishy in the calculation.

I seem to average about 14-16 mpg... low in the winter and high in the summer. The new tires I put on last year robbed me of about .75 mpg. My Yakima cargo box or ski rack lowers my mileage another 1 mpg or so. Bigger tires and wheels are heavier tires and wheels which take more power to spin, so that will reduce mileage too.

[kpaske]

Right, what VehiGAZ said - and most importantly, understand what iamjacksadrenalgland mentioned about having larger than stock tires - even if you are doing perfect calculations, your data is inaccurate because larger tires throw off your speedo/odo, so it may appear that you are getting much worse mileage than you actually are.

I've got 33" tires on 16" wheels, and I estimate that my speedo/odo are off by about 10%. Adjusting for that difference, I probably get 12-15 MPG on average.

[nfpgasmask]

I just ordered Tone's scan guage. I have never used a scan guage before so now I am wondering if it will give me accurate MPG calculations....we shall see. I'm really bad at math so I could use the help....

All I know is that when I get on the open road and drive for 2 hours at 85-95 MPH my VX CHUGS gas.

Bart

[Tone]

You'll need to use something like the miata garage tire calculator if you have changed tire size to see what percentage your speedo is off and then you can set the ScanGauge to take that percentage into it's calculations. I use MPH display of the SG on the dash of the '55 since I've gone to a taller tire. Keep the air pressure at max in the tires and drive conservatively but it is what it is and if you need MPG, this the WRONG vehicle.

BTW, stock tires are almost identical height/diameter on the 16" and 18". Come on guys, don't post INCORRECT information, it just confuses the newbies. Now the 18" rims could be heavier but I would not expect more than a few pounds - anybody have those specs? And if so, that would be more of an onroad handling issue when pushed.

1999 245/70/16 Diameter 29.5", 6.8" sidewall height (comfortable)
2000/01 245/60/18 Dia. 29.6", 5.8" sidewall height (less flex)

And yes, the wheels are interchangeable between ALL years.