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Buick Regal

Hi Guys

I have a 2004 Buick Regal with a 3.8 liter engine. It is a great car. When I first purchased it the gas milage was around 26 mpg on the highway. It has around 66,000 miles on it and does not burn oil. I use AmsOil 5W30 synthetic oil in it and that seems to be very efficient. I also use an AmsOil air filter.

I was wondering if there was something I could do to improve my fuel economy? It now gets around 24 mpg on the highway and around 21 or less in the city. Is there a different computer chip to increase my fuel efficiency and if so would it be worth it? I am considering changing spark plugs and wires. I have friends that tell me they get up to 30 mpg with their 3.8 liter Buick LeSabre on highway miles. Should I believe them? What do you think and what advice could you extend a guy who loves his car and would like to keep it for a while?

Why would a bigger car get better fuel economy with the same engine?

I would change the plugs and maybe the wires. I am not suggesting that they will increase your mileage, but I just don’t like to leave plugs in there that long as getting them out can be a real pain and unless they are long life plugs, they likely are well worn by now.

How about the air cleaner? When was it last changed? Have you bought new tyres? Some tyres deliver better mileage than others, and if you allow the air pressure to go low, it will reduce mileage and tyre life. Use the pressure indicated on the sticker or in your owner’s manual (Not the one on the tyre). You might consider going a couple of psi over, but don’t over do it.

I don’t know how you drive, but most drivers will gain the most mileage by modifying their driving style. Less aggressive and slower and avoiding using the brake pedal when possible will help. Frankly, from what you are reporting, I would guess you are already doing well.

I have a 1998 Regal and got 25 MPG on the highway during my commute. Yours is not much different. My FIL has a 2005 LeSabre and gets about 28 MPG on the highway. The quickest and cheapest way to get better gas mileage is to drive gently and don’t exceed the speed limit. I don’t know what your driving habits are, but most people still seem to go way faster than the limit, especially on 55 MPH roads. If you drive fast, which do you prefer? Do you want to go fast or get better mileage? They are mutually exclusive.

I doubt that you need plugs now, but check your owner’s manual for the change interval. It will be in the maintenance section.


I’ve kept a mileage/fill-up record since the day I bought my 05 LeSabre and I’ve noticed a 2-4 mpg decrease since just about every gas station has gone to the ethonol blend. I’ve seen some postings that going from 88 octane to the next higher blend has increased the mpg for some.

Bigger car = more weight + same size engine = less mpg