I was told by my dealer(back when I purchased my 98 Honda Civic EX)
That I would be wasting money buying premium gasoline, to buy regular. He also said I did not need to have oil changes every 3,000 miles. He recommended an oil change every 3,700 miles.
Could this be true?
Is it the quality of the vehicle that dictates this?
What does the owners manul say???
If the car doesn’t NEED hi-test then you’re wasting your money if you buy it.
With todays oils 5,000 is probably fine for an oil change.
Read your owners manual. If it says premium required, then use of regular could cause damage to the engine. If it says premium recommended, than you could use regular, but at the cost of reduced power and mileage (which could negate any cost savings of regular). Of course if you have been using the wrong gas for 10 years, it may be too late now.
Oil changes, follow the owners manual. Did he really recommend 3700 mile intervals?
What have you been doing for the last 10 years for gas and oil, and why are you asking the questions now?
don’t know what you mean by the “quality of the vehicle”?
Oil changes severe on your vehicle are 3750 miles(90% of owners fall here) and 7500 miles(normal). Premium is a waste in your and I believe spelled out in the manual. I am a former Civic owner.
You have a good dealer, he just saved you 5 trips to change the engine oil in the next 100k miles and nearly 8% in your fueling costs 
Your dealer’s advice is sound. The “quality” of the car has nothing to do with the matter of maintenance. It is the engineers who suggest fuel and maintenance recommendations for each model and they report it in your owner’s manual. Generally, the maintenance requirements are very similar for all cars on the market today.
What I mean by quality car is the opposite of crappy car.
A Civic is a very well made, relatively maintainance free car.
In reality the maintenance level of a Civic vs its peers is not better or worse according what the manual prescribes. In some ways worse than some peers due to $300+ timing belt changes.
I have owned two Civic’s to around the 200k mile mark and reality no better or worse than much else. I will say below 150k mark they required very little repair or unscheduled maintenance.