I'm doing a project about fuel efficent cars. I wanted to get ideas from you guys on how you make your car more fuel efficient. I'll take anything you got from nitrogen in tires to running 1/2 E85.

Thanks

Less restrictive breathing system (intake/exhaust), slightly over-inflated tires, driving habits

Spark timing while cruising. You advance spark timing and can gain a significant amount of fuel economy.

Water/alcohol injection to prevent knock, advance spark under highway cruising as mentioned earlier, and the water/alcohol injection actually creates a more dense mixture. This will improve fuel economy a bit, and reduce emissions as well.

Fuel rail heaters. Heating the fuel that'* going in is a bit difficult on a return fuel system, but hotter fuel ignites more easily.

Warm air intakes and 195-210 degree thermostats. Cold air intakes a great for power, but warmer air and warmer engine temperatures make for better fuel efficiency. I'm not sure why, but that'* what I've read.

There are tires that are made with a low rolling resistance. Low profile tires are generally low rolling resistance.

Lowered cars can also have slightly better fuel economy due to less drag hitting the tires. Not that great a difference, but every little bit helps.

Fabricate a plate to cover the rear spare tire well. A lot of air gets caught in the rear bumper.

Great! Keep them coming!

Do you have a source for that?

Don't need one. Over inflated tires are stiffer, causing lower rolling resistance, which means your car rolls more easily. Less power needed to keep it moving.

Lighten the car up. Just like if you were going to take the car to the track, you remove all unnecessary weight. Spare tire, jack, rear seat, passenger seat, visors, etc...you get the idea.

Also, less fuel in the tank = less weight on the car.

buy a prius?? Lol

lean cruise.. Ugh not legal in the US
loose weight (im a fatass, I can say that)
lightweight rims and tires

That'* easy. Keep car as light as possible, keep tires at proper inflation, Good clean properly gapped spark plugs. Clean filter, and driving habits.

Great! Thank you guys.

be as skinny as me.. that also helps in 1/4 mile time