Have a look at my signature; that is a pure, physically calculated number. My car normally gives 11-12 on long routes.
Start with the basics
- make sure that the car is properly maintained, with regular preventive maintenance performed (not just limited to oil and filter change, and desi 'toon up'). A working thermostat and auto fan are absolutely essential. If the catalytic converter is removed, don't expect too much fuel economy.
- switch to a low weight oil, preferably 0w-20 or 5w-20
- fill the tires to at least the max sidewall pressure
- get a Scangauge II, Ultragauge, or an ELM 327 w/Torque Pro app, or anything that displays fuel consumption, TPS, ignition timing, MAP, and %engine load. You may skip these if you want to install an i-VTEC detection light, but even then these devices are invaluable.
Look up i-VTEC and torque converter lockup. I will try to provide a rough working definition
- i-VTEC is an economy mode. In this mode, the throttle plate snaps open, the ignition timing retards, the cam switches to the economy profile, and you will see a huge boost in instantaneous fuel ecomomy.
- In an auto transmission, the torque converter serves a similar purpose to the clutch in a manual transmission. In normal driving conditions, it slips to multiply the transmitted torque. However, this leads to more heat generation and loss of fuel economy. The TC has a lock up mode which eliminates slip, and the loss of fuel economy associated with it.
Using i-VTEC at will is a very hard task, unless you use the instrumentation I have mentioned. Torque converter lockup is quite easy to use. First you have to know what TC lockup feels like. Follow these steps:
- take the car out for a test drive. Drive around normally until the engine is completely warmed up
- find a long, fairly empty stretch of road; Ring Road might be perfect for this test. Accelerate to any speed above 80 km/h, and hold it for a few seconds. Note the RPM. I think it goes at 2k RPM at 100 km/h for this car.
- Steadily give it more throttle in a matter of 3-4 seconds; the RPM will suddenly jump around 300-500 more than expected. Its almost like a slipping clutch in a manual transmission. Don't let the car downshift, so don't give more than 2/3 throttle or so.
- Leave the throttle completely, and apply it back slightly. Watch as the RPM settles back to its previous value.
You just witnessed TQ lockup and TQ slip. During lockup, the RPM stays at the lowest value it can for the gear and speed combination. During TQ slip, the RPM goes up around 500 over that value.
In my '03 Civic auto, the RPM is at 2500 at 100 km/h; it can slip and go to around 3000 at the same speed and gear. Play around some more with TQ lockup in your car, and note the speed and RPM combinations in top gear.
If you are in TQ lockup, chances are high that you are also in i-VTEC. During lower speeds, it becomes more tricky, since TQ has a minimum threshold for lock up. For most cars, that threshold is roughly 80 km/h.
To monitor i-VTEC at lower speeds, these devices are essential. Here is a video link below:
Combine this knowledge with some basic-intermediate hypermiling techniques, and you can get over 25 km/l on long routes.
--keep the car properly maintained
--use a firm and steady foot; don't accelerate and brake unnecessarily every few seconds