APPENDICES

Appendix A

Science

Driving Smarter: A High-Pressure Way To Get There Cheaper

Ask your parents if they remember going to the neighborhood service station. The attendants there would not only fill your tank with 30-cents-a-gallon gas, they would also check the tires. In those good old days, passenger car tires were mostly one size, and many service station attendants recommended inflating them to their 32-pound maximum. The tires would last longer, they'd say. Later, owner's manuals for each car became the authoritative guide. Tire pressures dropped to 24 or 26 pounds to yield a softer ride.

Well, with gas anywhere between $1.00 and 1.20, it is time to go back to 32 pounds, or whatever is the maximum pressure marked on the tire itself. This may be eight more pounds than the manual or the sticker on the door of your car recommends. The more pressure you put in your tires, up to the stated maximum, the less gas it takes to drive a mile. That is because harder tires have less resistance to rolling.

However, it is useful to maintain whatever difference in pressure between front and back tires the owner's manual recommends. For example, the manual might recommend 24 in front and 26 in the rear, while the maximum marked on the tire is 32. In this case, you should inflate the front tires to 30 and the rear tires to 32.

All tires slowly lose air pressure. One tire company checked 1,900 cars and found that 28 percent had tires that were severely underinflated. Tests conducted by tire companies and by others confirm that more pressure means better gas mileage.

One research group found that each two pounds of additional pressure in non-radial tires improves gas mileage by one-and-one-half percent. Because there may be a difference of eight pounds between the owner's manual and the tire manufacturer's maximum, this presents the possibility of a four to six percent gas saving. That's like reducing the price of your gasoline by seven cents a gallon.

These savings possibilities are for highway driving. In town, the percentage will be less, because of the time your car spends idling at traffic lights or being braked to a stop. The saving from increased pressure will also be less with radial tires. With radials, eight pounds of increased pressure yields about a two-and-one-half percent of fuel saving. Radial tires, however, give better gas mileage than non-radials when inflated to the same pressure. At full inflation, you should get about three-and-one-half percent better in combined city and highway driving.

To realize these savings, you have to keep your tires fully inflated all the time. This means checking them about once a week when the tires are cold (when the car has been sitting for three hours, or before driving more than one mile). You'll need your own tire gauge. One can be purchased for a couple of dollars. Why not get one for one of your parents for their birthday or other special occasion? Then you can be the tire expert in the family!

One last word: Fully inflated tires do produce a harder ride over bumps. But it does not damage the suspension system (as some people believe), and it does not shorten tire life. In some cases it will increase tire life.

Adapted from: Wind, Water, Fire and Earth; Energy lessons for the Physical Sciences, p.96

Oil That Works

There has never been a shortage of devices to add onto your car, or to put into your gas tank or crankcase, that claim to give you better gas mileage. Surprise! Some of them actually work, under some conditions. A few of them even pay for themselves in gasoline savings.

Among the most worthwhile "additives" are the new improved-friction motor oils. On the average, they improve gas mileage about five percent. That is equal to

Appendix B

Mathematics

DATE:
TO: Parents of Middle School Students
FROM: _______, Mathematics Teacher
RE: Data on the Family Car

In math class we will soon be starting a unit focusing on transportation. The unit will involve students in analyzing numerical data on the fuel efficiency on new cars. We would like students to use data from a family car. This data will be used to make determinations such as the fuel cost of driving to and from school each day and the total fuel cost for driving the vehicle each year. We have found that students have greater interest in assignments if the data with which they are working has some personal connection. For this reason, we are asking you to complete the attached form and return it to school with your child. Students will then have data to work with that is applicable to their own lives.

The goal of this unit is to increase students' abilities analyzing and interpreting their own data and to enlighten them regarding the fuel costs of driving. In addition, this knowledge will help students make wise choices when selecting their own vehicles in the future.

Thank you for your assistance in this matter. We will encourage each student to share their findings with their parents.

Family Vehicle Data Sheet

Student Name:
Make, Model & Year of Family Car:
Present Odometer Reading on Family Car:
Distance From Your Home to School:
Distance From Your Home to a Parent's Place of Work:
Approximate Miles per Gallon Family Car Gets:

Please return this form to: (Add teacher's name and address)