Step 1: Tires
Should you wish to go beyond, that is up to you. Personally, I inflate my tires to around 55psi (they are rated for 44). Please do not attempt on old or visibly damaged tires. My tires are new and in excellent condition.
Modern tires are radially belted - that is, they won't balloon like tires of yore. Keep in mind what you're doing though. You are reducing the contact patch of your tires in order to decrease static friction. This will reduce your overall braking ability. So riding someone's bumper at 80mph is just that much more dangerous. Again, these steps only work when combined - you can't pick and choose.
When it comes time to buy new tires, look for low rolling resistance (RR) tires. While they may not have the same 60,000 mile (or even 40,000) guarantee, they will save you in the fuel department. The Toyota Prius comes equipped with LRR tires.
Step 2: Weight
For those more daring, remove your emergency jack and spare tire and be sure to carry a cell phone in case of emergency. AAA is a good thing to invest in - even if you don't plan on following these mileage techniques.
If you won't be carrying passengers, remove your rear seat and passenger seat as this will lighten your load by a couple hundred pounds.
Step 3: Maintenence
O2 sensors are very critical pieces of equipment - especially the 1st one (primary).
If you have a check engine light (CEL) and your car is a 1996+ model (for US vehicles) - get your car scanned. Certain auto parts places will scan codes for free (such as Autozone). Fixing parts yourself can save a lot of money - that is, only if you feel comfortable doing it.
Step 4: Reduce Driving Loads
- Air Conditioning
- Loud Sound Systems
- Headlights (that means, try driving in the day rather than at night)
Step 5: Instrumentation
Nissan, according to internal testing, estimates gains in fuel economy ~10%
All New Nissan Vehicles will be equipped with fuel consumption instrumentation.
Toyota Estimates 5-10%, and They too will include instrumentation in new vehicles
Step 6: Pulse and Glide
Start at 40mph and allow your vehicle to decelerate, in Neutral, to 30mph -- this is called the glide.
Then, accelerate back up to 40mph in the same amount of time that your glide took -- this is called the pulse.
For the more intense, glide with your engine off. This will increase your FE number dramatically while gliding in gear will reduce them as you'll be combating engine braking.
This technique has been proven many times over to be an effective way to increase mileage. But, your mileage will vary based on traffic and other drivers. Other drivers will get quite pissed off at your pulse and glide, so use your best judgment.
Step 7: Hills
Step 8: Traffic Lights, Stop Signs, Traffic
The same goes for approaching a stop sign.
Step 9: Acceleration
Ideally, peak torque at 50-75% throttle.
Step 10: Aerodynamics and Modification
*Blocking your grille has proven to be effective - just remember that your radiator (and grille opening) were designed for the worst case cooling scenario. So monitor your engine temps and adjust your grille opening accordingly.
- Fold your mirrors. If you can, fold your rear view mirrors in. Just be sure to stay in compliance with local laws.
- Belly Pan - A significant amount of resistance comes from the open areas under your car. Covering them with corroplast or some other material can reduce your drag coefficient (Cd)
- Wheel skirts - covering your wheel wells to keep your cars body one contiguous object can help
- Air Dam - see image, if you car doesn't have one already, this can help
- Always Drive with your windows up
Step 11: Pretend you have no brakes
Coasting is your friend.
Step 12: Join a Community
Personally, I'm fond of the people on Gassavers. You'll find plenty of experiments that, quite commendably, follow a scientific method structure.