In my quest to lower my gas bill I realized buying a new car would negate any actual gas savings. Instead I looked for ways to lower the cost of the gas I do buy. 1. Buy from a warehouse club. Sams and Costco are .10-.20c cheaper than any other station in my area. (YMMV) 2. Pay with a rewards card. There are many that offer 5%, 3% or 2% back on gas purchases. If your getting 5% cash back on your gas purchase and a gallon costs $4 you save an additional .20c of each gallon! In reality you only pay $3.80! Couple this with the already discounted club rate and be the envy of your friends! 3. Top off each time your near the cheapest station but dont make a special trip if its more than a few blocks away. This is just what works for me and it has proven to be quite effective.
It might also be wise to buy a gas efficient vehicle. Another strategy involves making fewer trips. Finally, it's often possible, in the US at least, to see what gasoline prices are online. Therefore, a buyer can choose the station with the lowest price. Where I live, Kroger, Food City, and Wal-Mart have gasoline clubs. In that case, as you say, money can be saved by simply being loyal to one store.
That is good in your area. In our local place, reduced gas prices are hard to find. Filling gas station may sometimes offer promo for buying from them by giving freebies or giveaways but not in a lowered gas price. It would be a hard time on my part if I have my own car.
Gas here is getting too expensive which is kind off difficult to be paying with the small salaries one receives here. This is one reason I still can't own a car and mostly everyone owns a motorcycle or travels by bus. Some of my friends have cars but prefer taking the bus unless they are in a hurry because they save more in the long run this way. This is one of the major problems that is going on in my area right now, gas price increasing.
Our Mitsubishi Mirage is a people's car that has an engine of 1200 cc which is very economical compared to our old Honda Civic with a 1500 engine. The Mirage is 4 years old now and still runs 10 kilometers per liter. The old Honda was running 6 kilometers per liter because it is 20 years old. Hands down, a new car is a gas saver compared to old cars. Much better if the new car is a small one especially if it is meant to be used by only one or two persons.
Gas prices are climbing up here quite frequently. It is rare to find a single digit difference between gas stations. The only effective way in our area of gas conservation woukd be to not use your vehicle in daytime when the traffic is the worst and you could waste a lot of fuel just waiting in the queue. It is best to board a public transport instead.