Will my new car's fuel efficiency increase over time?

Question

I bought a 2008 Honda Accord EX-L 5 speed manual transmission in May 2008. I was wondering if the engine starts out at maximum fuel efficiency, or if fuel efficiency will increase over time? After 4000 km I'm averaging 26 MPG in city and 32 on highway. Specs say I should get 30 MPG in city and 44 MPG on highway. How many km do I need to drive the car before I reach max fuel efficiency. Also, should I be using British or US gallons in my calculations?

Thanks!

Chris

Answer 1

You might see a small increase in fuel efficiency after the car has gone through the breaking-in period, during which the moving parts in the engine settles into its normal wear pattern.  Perhaps a 1 MPG improvement or so, if that.  After that, you will probably see the fuel efficiency decrease as things like the engine air filter starts getting dirty and such.

The U.S. EPA mileage estimate for your car is 22mpg city / 31mpg highway (using U.S. gallons).  I'd say what you are seeing is about right.

Answer 2

No it will not. Actually, fuel efficiency will decrease after about 100,000 miles. Your driving habits affect fuel efficiency. Do you step heavily on the gas when the light turns green? This type of irregular driving style reduces fuel efficiency.

Answer 3

you should improve around 15000 miles, or 24000 kilometers.

for that fuel economy they used british gallons to calculate it, so you should be using them for comparison...

also, the way you drive will affect our ability to match that fuel economy.  they are generally obtained by very specific manners which few people ever duplicate.

Answer 4

They can improve after a while.  I've had a couple that did that.

Probably, though, driving style has about 10 times the effect as wear and tear.  On the highway, you probably would have to slow down.  Not that I care, but it's a long way from 32 to 44, so you need something dramatic, and air resistance goes up by the square.