Q: I’ve wondered for a long time why most automobile manufactures include a tachometer in their instrument display. What frustrates me is that they eliminated instruments that are useful, i.e., temperature and oil pressures gauges. Are tachs useless?

A: In verhicles with automatic transmissions — which these days is most if them — it really doesn’t have a practical purpose. Sometimes I glance at the tach to see if the engine is running. Never try to start an engine that is running.

Uncooperative gauge

Q: My wife drives a 2018 Toyota RAV4 Hybrid and has experienced issues with an inaccurate gas gauge. Starting at roughly 50 miles after filling up the tank, the gauge will drop to empty and will slowly climb back up until 100 miles or so. The dealer tried resetting some related software, but it seemed to have little effect. Their next step would be a repair that involves dropping the gas tank and replacing the fuel sender unit, but at my own (considerable) expense. Is there any other possible solution?

A: Try the simplest option first. Pour a bottle of fuel system cleaner in the tank. Give it several days; this may help. Otherwise, look for issues with the wiring outside the tank. The worst-case scenario is, of course, lowering the tank and replacing the fuel level sender.

Old or new?

Q: I own a 24-year-old car, which has been good to me, but major things are starting to break down. It has 110,000 miles on it. I have been considering a sedan in the $15,000-$18,000 range, less than eight years old, but all the ones I see advertised have over 100,000 miles on them, which is the same as my car and likely means they were traded in because they were starting to run up repairs. Would it be better to opt for a two- to four-year-old car that someone trades in just to have the latest model?

A: There’s more involved than just the mileage. A newer car will have newer safety features. I have seen cars of a more recent vintage go well over 200,000 miles with regular maintenance. One option is to buy a certified used car that comes with a warranty that’s nearly as good as that on a new car.

Bob Weber is a writer, mechanic and ASE-certified Master Automobile Technician. His writing has appeared in automotive trade publications, Consumer Guide and Consumers Digest. Send automotive questions along with name and town to motormouth.tribune@gmail.com.