题目内容：

    As the summer travel season rolls in, prices at the gas pump are usually going in the wrong direction for our wallets. That’s when drivers become more concerned about how to squeeze the most miles from their fuel dollars and keep their cars running their best. To help you stay in the know, here are some common questions that our auto-experts often get asked about gas mileage and related topics:

What if I need to carry stuff on my car’s roof?

Carrying things on the roof hurts fuel economy. When tested a 2013 Honda Accord at a steady 65 mph①, it got 42 mpg② with nothing on the roof. Adding even an empty bike rack（架子）dropped the mileage by 5 mpg. And with two bikes on the roof, gas mileage dropped to 27mpg.

Does running the A/C① hurt fuel economy compared with opening the windows?

It depends on-how hard the air-conditioning system has to work. When we measured the fuel-economy difference, we found that fuel use with the A/C running went up with higher outside temperatures. At 55℃ F, there were unnoticeable differences. But when we measured again on days when the temperature was in the low 70s and high 80s, we got fewer miles per gallon with the A/C on.

How far can I go when my low-fuel warning light comes on?

There is no set rule, but most cars have a reserve of between 1 and 2 gallons of gas when the light goes on, or enough to travel about 40 miles or so at a moderate speed. To maximize those last couple of gallons, we suggest slowing down and maintaining a steady pace.

Can I improve gas mileage by installing a special air filter（过滤器）?

With modern cars, changing your air filter probably won’t improve your fuel economy. When we tested a car to see whether a dirty air filter hurt its gas mileage because of reduced air intake, we found that the car’s fuel economy wasn’t hurt. The engine’s computer automatically made up for the restricted airflow by reducing fuel use to maintain the right air/fuel proportion. We expect similar results from any air-filter change.

①mph: mile per hour

②mpg: mile per gallon

③A/C: air-conditioning

1.The passage is intended to give answers to questions related to _____.

A.how to save fuel

B.what fuel drivers can use

C.how to keep cars working well

D.what mileage is most suitable for a car

2.It is suggested in the passage that ______.

A.a special air filter be installed to improve air intake

B.the engine’s computer be updated as often as possible

C.drivers carry an empty bike rack on the roof just in case

D.cars move at a fixed low speed with a warning of low fuel

3.At which temperature is there a most noticeable difference in fuel economy between running A/C and opening the window?

A.40° F B.51° F

C.55° F D.73° F