is this true?

**web99992002** · December 28th, 2007 11:32 PM

totoo b na nag iimprove ang fuel economy kpag mas lumuluma ang kotse? let's say pag nka 5K or 10K service?

**Hayward** · December 29th, 2007 12:12 AM

To me it has a lot to do with a person's driving habits like avoiding jackrabbit starts, light foot on the gas pedal, no prolonged idling, no sudden braking, etc.
Most if not all new cars today have already undergone the "break-in" period before a buyer gets his hands on it.

**mbeige** · December 29th, 2007 11:30 AM

The only truth to that is if the car is brand new, after it's broken in it will have better fuel economy. The rest all depends on driver usage, maintenance and current condition.

**pup2** · December 29th, 2007 01:35 PM

I feel though, that my cars usually have better fuel economy right after each PMS. Perhaps it's mostly the PMS that does it? (after break-in) I don't know if any studies have been made though.

**mbeige** · December 29th, 2007 02:04 PM

Well certainly after a service has been done the car will perform more efficiently and better, hence the reduction in fuel consumption. But to say that it gets better fuel consumption due to age alone is false; if any, it will get worse if nothing has been done for maintenance. Older cars will need to eventually have the valved adjusted, the timing checked, sparkplugs replaced, etc. Newer cars will have more sensors so if these sensors go bad it can send bad feedback to the computer which results in changes caused by faulty sensors. For example, mass air flow sensors can get bad especially if used in conjunction with K&N filters (the cleaning solution on the filter can ruin MAF sensors). Or another, oxygen sensors need to be replaced eventually.

Once the bad parts have been replaced as in a PMS or maintenance due to bad parts, then the car will perform better.

**niky** · December 29th, 2007 04:54 PM

There's a sweet spot about 10,000 - 20,000 kms after purchase, wherein the car's engine is in peak condition.

I've heard the same thing from the SAs that cars are broken-in from the factory... but what this really means is that engines nowadays are assembled with tighter tolerances and are dyno-tested before delivery... which means that unlike older engines, they don't need such extensive break-ins (unless they're high-revving performance models, some of which, like BMW's M5, should never be redlined until properly broken in).

But this doesn't mean that engines are perfect from the factory... an engine's peak performance is attained some 20,000 to 40,000 kilometers after delivery. I've noted in testing that test vehicles with fewer kilometers on the odometer actually make a little less power than "seasoned" testers (this is from instrumented road tests). This observation has been made by various testers like Car and Driver, too... and many owners of new cars report increasing fuel economy as the cars get older.

**pup2** · January 2nd, 2008 07:20 PM

Oops. Sorry for the double post.

**pup2** · January 2nd, 2008 07:20 PM

Originally Posted by niky

There's a sweet spot about 10,000 - 20,000 kms after purchase, wherein the car's engine is in peak condition.

I've heard the same thing from the SAs that cars are broken-in from the factory... but what this really means is that engines nowadays are assembled with tighter tolerances and are dyno-tested before delivery... which means that unlike older engines, they don't need such extensive break-ins (unless they're high-revving performance models, some of which, like BMW's M5, should never be redlined until properly broken in).

But this doesn't mean that engines are perfect from the factory... an engine's peak performance is attained some 20,000 to 40,000 kilometers after delivery. I've noted in testing that test vehicles with fewer kilometers on the odometer actually make a little less power than "seasoned" testers (this is from instrumented road tests). This observation has been made by various testers like Car and Driver, too... and many owners of new cars report increasing fuel economy as the cars get older.

Seems to indicate a bell-shaped efficiency curve for engines then eh Niky? Maybe slightly skewed to the left?

**niky** · January 2nd, 2008 08:40 PM

Depends on use. I'd say to the right. Some people are still getting good dyno numbers from 100k - 200k engines, due to diligent service and the use of good synthetic oils.