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Definitions: Direct Injection

Pros: Direct injection improves both power and fuel economy by making the engine more efficient.

Cons: Costs more; engineers are still working out the kinks

Summary: If you’re shopping for a car and you see the term “direct injection,” it refers to a system that channels fuel into the engine more efficiently than conventional multiport fuel injection.

Direct fuel injection (DI) was invented more than a century ago, but it has only recently emerged as a trendy automotive technology. The reasons for its popularity are clear: It improves both acceleration and fuel efficiency. Sounds like a win-win situation, right?

Mostly, it is. DI engines are impressive already and getting better by the year, so there’s no doubt that the technology is here to stay. And DI is available on cars of all pedigrees, so whether you’re looking at a Kia Sorento or a high-end Lexus, DI will be in the mix.

However, there are some drawbacks worth mentioning.

First, there’s no such thing as free horsepower and miles per gallon, so you won’t be surprised to hear that DI engines cost more than comparable conventional engines.

And then there are the inevitable growing pains as engineers get comfortable with modern DI technology. Audi had some issues with carbon buildup in the engine valves, for example, and BMW was burning through a lot of fuel pumps for a while. It’s still a hotly debated question whether DI engines are as dependable over the long haul as regular ones. The answer is probably “yes,” but just keep in mind that it hasn’t been perfectly smooth sailing for DI thus far.

AutoTrader Says

You can buy DI with confidence, as the pros outweigh the cons. But make sure you follow the manufacturer recommendations for special treatments, fuel additives, scheduled maintenance and so forth.

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  1. A 1.6 L DOHC L4 may have 115 HP; however, with DI maybe 140 or 150 HP. I say the gas mileage is actually better. Why? If you were to upgarde the non-DI to make it 140-160 HP (Honda Civic SI of old) then the gas mileage will suffer. Therefore: the DI 1.6 gives you better performance than the non-DI 1.6 but the same gas mileage; but the and upgraded non-DI 1.6 gives you the same performance as the 1.6 DI but less gas mileage. If driven the same way gas mileage conscious drivers do the non-DI 1.6 do then the 1.6 DI engined cars would easily exceed the mileage of the non-DI. There are some well known Canadian that proved that Hyundai Sonata-for instance- actually could get in excess of 50MPG. Yes, those to Yahoos did some pretty extreme driving stuff but also were able to achieve high mpg without violating the law. It’s how you drive not what you drive, remember. Proven over and over again. I know lot’s of people that have the Prius but few get better gas mileage than my 09 Civic. One or two do get 50-70 MPG because they drive that way. Top Gear UK did a race between a BMW M3 and a Prius. The Prius could run at full throttle and the BMW had to only keep up. Both cars were topped off prior to the set number of laps. The BMW averaged 21 MPG…the Prius 17 MPG. About your V8s, much is true…

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