Turbo engines get "worse" mileage than the non-turbo version of the same engine, but up to double the HP , so actually, you have more efficiency per horsepower! :) and much better mileage than a larger cubic engine that has equal hp.

PS Our turbo 2.0 Direct injected engine is rated higher mileage, 21-29, than the 2.4 non turbo HHR engine's 20-28. (both 5 speed 2008 EPA figures.)

 

Actually, its quite usefull as I have found on my Corvette. The average is over the last however many miles, but the instant is just that: exactly what you are getting at that minute. If you are stopped, 0. If you are going down a hill, 70, 80, or so because gravity is doing the work, the throttle is closed, and if an auto, the rpm is lower.
The cool part is, you can cruise at 60, see what you are getting, cruise at 70, see the difference, cruise at 70 with the ac on, or off, windows up, windows down, or in 3rd gear, or what ever, and as long as you are on flat ground with steady wind directions, you can observe your cars behavior over many conditions. An interesting question for you: when taking off, is it better to accellerate fast, get 3 mpg, but for only the 6 -8 seconds it takes to get to 60, then cruise at 30 mpg, or is it better to accellerate slowly at 5-7-10-14-17-22-25-27-30 mpg but take 30 seconds to get to the 30 mpg point? Humm

 

Having been a member of the Saab Classic 900 board for many years, I can give thousands of examples of owners of turbocharged versions of identical cars getting BETTER mileage that the naturally aspirated version. Turbo power being called free energy, as it generates power & is driven by the exhaust, a waste product, as a supercharger is normally belt driven CONSUMING horsepower as it operates

 

Fast starts are a killer for milage. If you go 80 to get there faster you won't save gas over going slower and taking longer to get there either.

 

I just bought a 2007 2LT. I had been test driving 08s... so I was dissapointed when I saw Instant MPG wasn't on the DIC, especially since my family had a 2003 Monte Carlo with that feature. But anyway - like people said 'what are you getting at this speed/condition?' can be helpful.

For those with just the AVG readout DIC - just hold the reset and you'll get an 'instant' reading for a moment =).

 

Originally Posted by diskullman
Yes, but the vacuum guage's main purpose is as a boost guage. Supposedly a turbo is a gas saver because it is free energy. It may be interesting to see how instant mileage reacts as you are in boost, instead of vacuum.

A Vacuum guage is NOT a boost guage and has nothing to do with boost. Boost is pressure...Not vacuum.

Turbos do not take engine power to operate as a blower does, but it is not free power... It take exhaust pressure to opperate.

 

Gee thanks for enlightening me Bob. I guess all the folks that bought vacuum/boost gauges from me are SOL!. The same gauge, and connections are used for vacuum and boost guage. Boost is the opposite of vacuum. As one can plainly see from the photo, the negative side of the guage is VACUUM, the posative side of the guage is BOOST or PRESSURE.

The "free" power statement should probably be"recycled" power. It's not as if your engine will NOT produce exhaust pressure if you do not have a turbo, unless you don't start it up.

 

You can use the instant MPG to collect data points based on temperature, head winds, tail winds, etc.

I've actually recorded this and it is amazing to see just what a moderate head wind will cost you or the MPG difference between 15 degrees and 55 degrees.

You think I'm a nerd, don't you?