New Kei car owner, wants better mpg.
 

I just joined the ranks of Kei car owners with a Suzuki based Hyundai Atoz Prime. Sadly though, I am only touching 35 mpg US with it. It runs perfectly, timing is spot on, no check engine lights, and all the maintenance is done. I was hoping for better since it has no power steering, or A/C, but it is an automatic w/o tq converter lockup. Apparently the manual version is only rated at 38 mpg US so I've been told that I should be happy...:(

Anyway, I know the modding principles are the same with most cars, but I am wondering from other Kei car owners what mods gave the most benefit in fuel economy first so I can start from there.

Currently the car is bone stock (has no power steering, no A/C as mentioned), a new air filter, plugs, wires, timing belt, cam/crank seals, runs semi synthetic oil 15W-40 and....that's it.

If anyone has any tips, I'd be happy to hear from you fellow Kei car owners. I love the thing but am a little disappointed with the mileage.

THanks!

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I guess it depends on what kind of driving you do (sitting in traffic jams, for instance) but I'd be surprised if you couldn't beat those numbers just with some of the hypermiling tips on this site. I wouldn't have believed it myself, but just by changing my driving style I'm getting an extra 150 miles out of a tank of gas.

I also suppose it depends on what kind of gas you use...I am not sure what you have in Cambodia. If the ethanol is higher, the numbers will be lower.

Can you use thinner oil? Check the owners manual. My '97' Honda calls for 5W-30 and most newer cars call for even lighter oils.

Added a picture of the car to your post. Neat little machine.

Non-locking torque converters are the bane of automatic transmissions.

First bit of advice: get instrumentation. I'm not sure if the car is OBD-II equipped (for ScanGauge, Ultragauge, etc).

I'm aware that driving habits play a huge role in economy, and this car frankly is very dependent I imagine on the drivers foot. The automatic in this car only has three speeds and it's a very "lazy and slippery" transmission, meaning that it shifts very quickly into top gear (around 17-19 mph) but in so doing can vary rpm from 2200-3500 depending on how you mash the gas pedal. Also, no tq lockup plays a big part I am thinking. Also, while I try to keep the car at slow speeds, because of the minute 790cc motor, I am usually unable to keep it below 3000 rpm, whereas my old Toyota could be kept completely under 1800 the entire time.

As for the oil, I am not sure. I imagine 15W-40 might be too thick, but honest to goodness, I have no manual and can't find one online either. Fuel that we have is pure gasoline, no ethanol. That's why it's almost $6.00 gallon here!

I guess I'll have to get used to it as I only have 50 horsepower now to play with. :)

EDIT: ^^Added a "Thanks" but I like mine better. ;) Also instrumentation would be great, as all I have is a temp, fuel and speedometer gauge. As you might imagine though, aftermarket gauges are a little hard to come by here.

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Get some lightweight racing wheels and try to remove all the other unnecessary weight. If you only have 50hp (albeit in a small car), make those horses work less!

Looks like it's 4x114.3 so RX-7 and AE86 wheels might fit if the offset is right.

Air up the tires. Not sure on these small ones but most of us run 40+.
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Sounds to me like the #1 problem is the slip-slidey automatic. Heck, a carb'd '84 Tempo with no OD, converter lock, and 3-sp auto can touch 35 on a good day. Is there something wrong with the transmission?

The lil engine simply is going to rev higher than your old Toyota, no matter what. It wants to. The short stroke causes the happiest piston speed to occur at higher revs.

Quite surprisingly for me to know that the automatic transmission was available for the basic versions of the Atos without aircon or power-steering. In Brazil it was available either with the manual, the semi-automatic or the full automatic, and the automatics usually had all the comfort features...


It might be very low-geared to provide quick acceleration on urban traffic, and these small tyres also seem to keep the final drive ratio very low...

Wondering if it's slippy due to defect or design.