85 Riviera T Type

[cracker]

I recently purchased a 85 Riviera Convertible with the V-6 TURBO. The fuel mileage is about 13MPG around town. Is this normal for the car and if not do you have any ideas as to how the mileage might be improved?

[NTX5467]

Fuel economy is HIGHLY affected by "Idle Time" and acceleration periods, much of which could be operative in "town driving". This is really illustrated in a modern vehicle with an "Instant Fuel Economy" and "Average Fuel Economy" readouts from the onboard trip computer.

The best way to determine if an engine's "up to snuff", efficiency wise, would be to find a gas station near an interstate highway or regional loop. Fill up the tank, hit the freeway, set the cruise and drive in a general speed range that is fast enough to be "with traffic" for about 60 miles or so. If there's a regional loop, it works well for this during off-peak traffic times and tends to negate the effects of wind and such. When you get back to the original gas station, then clock the mileage and fill up the tank. This sort of test is a much better determiner of whether or not the engine is working "as designed" (in something of a "steady state cruise" situation) rather than "town driving". Sure, mpg is important in town driving too, but driving style and the "stop and go" factor can make a normally economical vehicle into a "hog" of sorts.

The other side issue is that most gasoline engines start getting into their "efficiency zone" at about 2000rpm. Town driving will most probably let that happen "not very much", especially in a high gear steady speed situation.

In a new Lesabre Limited I rented back in the summer, I determined with the help of the onboard trip computer, that moderate acceleration to the posted speed limit (or traffic flow) and then immediately backing off to maintain that speed can result in the best instant and average fuel economy in "town driving". Using the "coast" orientation after reaching the target speed helps too, when possible.

In general, make sure the front end alignment "toe-in" is set as close to possible to "zero" within the factory specs. Making sure the tires are inflated to the 28-32psi range will help too.

Just some thoughts,

NTX5467