Si and EX are my choices now. I read plenty of premium gas vs regular gas dicussions here and clearly see that T&R are up against some pretty fierce dissenting opinions. Here is a new angle to the dicussion: Why buy a toy (Si) when I am so concerned about the cost of running it with premiun gas and whether regular gas would reduce the power, cause pinging/knocking, and MPG dive (or not, according to T&R)?
There really aren’t significant dissenting opinions. If it’s required, the opinion is that you use it. If it’s recommended for optimal performance, there may be some debate.
The Si is faster than the EX and is more fun to drive. Premium gas is REQUIRED, period. At best, you will not get the performance and fuel economy the Si is capable of providing. At worst, you will do expensive damage to its engine. The EX is cheaper to run because it gets more miles per gallon and runs on lower priced regular.
It is incorrect to call the Si a toy since it has the same utility as the rest of the Civic line. The Si is just sportier than the other models. You need to decide which means more to you, the fun of driving the Si or the money you can save driving the EX.
We have a 2003 Toyota 4Runner with the V-6 engine. The owner’s manual specifies that 87 octane may be used, but for better performance, one may want to use 89 octane. My wife watches the mpg display like a hawk. She also thinks I accelerate too hard. If I’m driving and she isn’t looking, I fill the tank with 89 octane–if she is going to drive I fill the tank with 87 octane. There is a slight increase in mileage with the higher octane, probably not enough to justify the extra cost. However, using the 89 octane I can equal or beat her mileage. Of course, if she figures out what I do, then I’m sunk.