TOM: Completely. The higher the engine revs, the more fuel it uses. It’s like walking. On the same terrain, the faster your legs move, the more calories you burn. And the same is true for your engine.
RAY: That’s why, in chasing better fuel economy, carmakers have continually added more gears. In the 1950s and ‘60s, most cars had three-speed transmissions. The Ford Focus we drove a few weeks ago had a six-speed automatic. And the BMW X3 we drove last week had an eight-speed!
TOM: Why? Because the higher the gear, the fewer times the engine has to turn for each rotation of the car wheels. And the slower the engine turns, the less fuel it uses.
RAY: If your friend is really thickheaded, Marie, and refuses to concede, suggest that the two of you take a bike ride. Find a couple of 10-speed bikes (which won’t be easy, because even bikes now have 21, 24 and 27 speeds). Then find a nice, flat road to simulate a highway.
TOM: Then set the rules: You get to use all 10 of your gears, but he can only go up to 3rd gear on his bike. Then race a mile. While you’re pedaling easily and your bike is moving quickly, he’ll be pumping his legs furiously and struggling like crazy to keep up with you.
RAY: At the end of the race, when he’s exhausted, sweating profusely and doubled over trying to catch his breath, ask him how much “fuel” he used keeping up with you, and then collect on your bet, Marie.
Run-flat tires are the best option when tires keep getting punctured
Dear Tom and Ray: Between yesterday afternoon and this morning, I have had three flat tires. The tire that was flat yesterday had a screw in it, and the tires that are flat this morning have finishing nails. Other than the obvious question of “Was this sabotage?” I have a question about repairing the tires. My question is, are plugs reliable, or are patches or tire replacement recommended? I will add that I am living in Costa Rica, and tire puncturing is a known technique for robbing foreigners. Thus the idea of replacing tires only to have them repunctured is not appealing. But even less appealing is having to stop along a highway (they do not have shoulders) and being held up by the people who put the nails in the tire. — Bill
TOM: Well, my first thought was that you need run-flat tires. But I’m not sure that technology is widely available where you live. Run-flats require special equipment to mount them, plus they’re expensive, require tire-pressure monitors and may not be as repairable as standard tires.
RAY: So, on second thought, you need a 55-gallon drum of pepper spray mounted on the roof.
TOM: Actually, plugs have been used since the days of the Roman chariots. OK, not that long, but they’re well-established and effective. As long as the hole in the tire is not too big (and screw or nail holes are not too big), you can insert a plug and expect it to last for the remaining life of the tire -- which in your case sounds like about six hours.
RAY: But even better, a plug is something you can do yourself, Bill. You can go to any auto-parts store (try Manny, Mo and Carlos in Costa Rica), and buy yourself a plug kit.
TOM: It consists of a bunch of plugs, a reamer, which you use to make the hole the exact size of the plug, and a tool for inserting the plugs.
RAY: So you create the hole, then thread the plug into the insertion tool, and then you insert it and remove the tool. And voila! The repair is done and you’re on your way.
TOM: So then what you need is a cylinder of compressed air that you can carry around in your trunk. Once you plug your tire, you can reinflate it by the side of the road, hand your wallet to the nice banditos who’ve been waiting patiently for you to fix the tire, and be on your way. Good luck, Bill.
Send your comments or questions for Tom and Ray to: Car Talk Plaza, P.O. Box 3500 Harvard Square, Cambridge, MA 02238. Listen to them Saturdays at 10 a.m. on 91.3 FM or 88.5 FM. Visit them on the Internet at www.cartalk.com.
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