My SSEi got about 23-25 mpg my last tank, and that was mostly around town (though around town requires me to drive 5 miles at around 70 mph).

I know your going to raise the BS flag on me for this one but the wife pulled 37 MPG last week in my Bonne.

You do the math

243 miles
6.5 gallons

is the l27 supposed to get better milage/fill than the ln3?

i regularly get 28 mpg or 10km/L in a mixed highway and city drive.
i think i can actually get 30mpg just never tried to.. i will let it see how far it goes before it dies.

step one... un junk the trunk
step two... junk the o2 sensor <unless that is fairly new>
step three... junk the brakes <unless they are not dragging none>
step four... start walking <you will decrease driver weight and save on gas. j/k :P >

NEVER!

I average 19mpg to work and back. On the highway I get27mpg.

No BS here, in my old 88 Royale, I once got 38 and change. That was serious grandpa driving though, take forever to get to speed, recent synth oil change, no AC (cool outside) It was a round trip, same gas station and pump used in the same day to calculate (250 mile round trip)

Couldnt believe it myself for awhile. it was averaging 30 or so normal driving anyways.

My wife was driving an average of 80 MPH with a top speed of 90, and plenty of WOT passing, but over 200 of the 243 miles were highway.

but it'* not rare to pull over 30 MPG highway in my car, pushed it into the 40s with a little drafting off a semi on my return trip from North Carolina once
OK OK, I'll end this hijack, I know, this thread isn't supposed to be about MY MPG

OK, Here'* a little tidbit I put together to answer the regular question of "how do I increase my gas milage." Take it for what it'* worth. All info is supported by many publicly available sources and personal experience. In no particular order of importance.
________________________________

Fuel Saving Tips

1. High Performance Exhaust. Replacing a stock muffler with a high performance muffler or cat back system can help fuel economy. Most stock or OE exhaust systems bog down the performance of your vehicle. Note that this particular tip does not apply to our Bonnevilles as we have a high-flowing exhaust already!

2. High Flow Converter. Replacing your converter on your higher mileage vehicle is a great way to enhance the performance of your vehicle. Over time converters can become plugged up and greatly reduce fuel economy.

3. Air Intake. Make sure your air filter is clean. A dirty air filter keeps your car from being able to breath, reducing efficiency. Replacing your stock air filter is a great way to increase your fuel economy. Another bigger approach would be to replace your air filter with a high performance intake kit. If your car is so equipped (Bonnevilles are), make sure your IAT sensor and MAF sensor are clean and working properly. Ensure that your throttle body (or carburator if older car) is clean and working properly.

4. Spark Plugs. Make sure your plugs are clean and the correct kind. Replacing your platinum spark plugs with some high performance iridium spark plugs may also increase fuel economy. In the case of the Bonneville, AC Delco and NGK are recommended. Bosch plugs have proven to be problematic to many who have used them in their 3800s.

5. Tire Inflation. Keep your vehicle'* tires properly inflated. Low tire pressure reduces fuel mileage and increases tread wear. It is estimated that you can lose up to 6% in fuel efficiency with under-inflated tires.

6. In Tune. Keep your vehicle tuned up. An engine that runs roughly or misfires from plugged fuel injectors, bad spark plugs or wires, or worn and cracked distributor/electrical components reduces performance and fuel mileage. Make sure that your emissions system is working properly with no vacuum leaks and that your PCV valve is clean and working.

7. Stay Balanced. Keep your vehicle rolling smoothly. Make sure your vehicle'* tires are balanced, the front ends are aligned and the brakes aren't dragging. The added rolling resistance from improperly adjusted tires, brakes and alignment can cut fuel economy by as much as 20 percent.

8. Oxygen Sensors. Check your O2 sensors. A new oxygen sensor alone can improve gas mileage by as much as 15 percent. Again, in the case of the Bonneville, stay away from Bosch O2 sensors and try to get AC Delco if possible.


*All tips above are recommendations based on past experiences and I cannot guarantee actual improved fuel economy. It has been my experience that doing the tips above will improve fuel economy but there are so many other variables involved that I cannot guarantee it. Percentages quoted are based on information found in public domain sources. These tips are meant to be helpful and potentially save you some money at the pump!