So I just bought my used 2002 Volvo S40 which as you know has a turbo. The car has 100,000 original and runs great (except for my turn signal issue). It seems to be getting 23-25mpg on the highway and about 19mpg in city driving. I have been using premium since I bought it 2 months ago but is it really necessary?

 

No, it is not required. You can run 87.

 

I put in 89 today. I read that it is good to alternate between 87 or 89 and 93. I will try that unless someone feels that is not needed. I am not looking for any kind of high performance. I just don't want any knocking or pinging. Thoughts?

 

The car runs fine on 87. My daughter has been driving my 2001 for 5 years and it's seen nothing but the cheap stuff.

Modern engines have very good anti-knock control.

 

thanks Houdini. Will do.

 

Alternating will do nothing but cost you more money to fill up.

 

The car will run on 87 but with somewhat reduced performance and fuel economy. As mentioned, the car has a knock sensor. If the engine starts to knock, the computer will back off the timing to prevent knocking. Performance may be acceptable and with the difference in price between the regular and premium, it may be worth the hit to fuel economy.

 

It will not change fuel economy.

 

It did with my '02 S40 and first '05 V50 T5, to the point that economically it was a wash using regular or premium. That was when there was only a $0.20 / gal difference between the two. Now the spread is greater and it is likely economically cheaper to run regular.

I track all my fill-ups in Excel recording what fuel, calculating based on gallons replenished and miles between fill-ups, not the cars trip computer. I do record the trip computer value to see how well it tracks though. It is usually < 1 mpg off.

 

I always use Premium it's about 2.65/Gal in NJ. It costs about $25 bucks to fill up and I get around 450 miles to the tank. I do a lot of city driving and that really hits the gas hard but on the highway I normally get 30+ mpg. Even more with CC on. I put regular or special in the car when times get tough but for the most part the extra $2-$3 for Premium is good. I always use Mobil if that means anything. Every 2000 miles I run Lucas treatment.

 

Okay, I'm not getting into this argument again.

 

Same here, I'm out

 

So I used the 87 this week. I drive about 600 miles per week for work (highway miles). I noticed no difference between the premium and regular unleaded grade as far as performance. No knocking or pinging. Gas mileage is about 24mpg which is about the same as what I got using premium gas.

 

here's the funny thing about premium fuel - many blends use ethanol as the way to increase the octane (aka improve the resistance to ignition by compression) which has a lower energy density than gas (ie octane). SO its actually conceivable that your mileage could go down (same reason "winter blend" fuel lowers your mileage).