The regular change of oil will not significantly show any change in fuel consumption, if considered over short period. The regular oil change will help in maintaining good engine health and power. It will also increase engine's life. In long term there will be saving in consumption of gas.
If the car was taken care of and serviced regularly then this is not really high mileage. It is not low mileage either. Expect to spend money on some repairs on a car with this mileage. If the car has been neglected then this is high mileage.
No. A car will get better mileage with the correct tire pressure.
Gas mileage in any car depends on many things. Some are: How hard you accelerate. How well maintained the car is. Long or short journeys (short give worse mileage). How heavily loaded the car is. Whether you have a roof rack (without gives better mileage).
for any car to get better gas mileage get a better flowing intake and/or exhaust or get it tuned
To determine which car has better gas mileage, we calculate the miles per gallon (MPG) for each. Car A has a mileage of 25 MPG (125 miles / 5 gallons), while Car B has a mileage of 20 MPG (120 miles / 6 gallons). Therefore, Car A has better gas mileage than Car B.
If this car was serviced regularly and taken care of as it should have been then no this is not high mileage. But if this car was neglected and the oil/filter was not changed regularly then this could be considered high mileage. Most cars built within the last 15 years can easily reach 200,000 miles with no major repairs if they are serviced regularly. So, the bottom line is that it depends entirely on how the car was serviced and how it was driven.
get a better car
Yes, in fact, rotating and replacing tires regularly is essential for maintaining your car's optimum gas mileage.
better gas mileage
Many times a high mileage newer used car is much better to buy. The miles are most likely highways miles which are way easier on a car than city driven miles, which is mostly stop and go traffic, and the book price is reduced according to mileage making them an even better deal.
The best gas mileage from unleaded gasoline or premium gasoline depends on the car. Old cars get better mileage from unleaded.
Diesel.