Without the turbo,it’s acceleration would be even more dismal than it already is. When its spooled up on the pipe at high boost, it goes pretty good, but only gets about 26 MPG on the highway. Thats at 75-80 MPH.

Now if I accelerate slowly and keep the revs under 3000, (65 MPH) the thing easily gets 33 MPG and if I play a few hypermiler games like coasting down hills and cutting off the A/C when climbing hills, it will jump up to about 37 MPG and has gotten as good as 40.

Bottom line is any pressurized engine, turbo or supercharger is going to use more fuel at high boost tha a comparably sized naturally aspirated engine. If the computer didn’t increase the fuel flow to match the air flow, the engine would run way too lean and eventually destroy itself.

The small turbo engine realtive to the size of the car will be as good or as bad as the driver makes it. It has ther potential to go either way.

Plebes rejoice!!!

The new 2009 2.2 L Cobalt now has variable valve timing which bumps the HP to 155. And yes, the aforementioned 25/37 MPG. No pedestrian Civic, Corolla, Yaris, Fit, Sentra, Versa can touch this combo. And forget about drag racing against the Cobalt, you WILL lose….

Now imagine this:

GM has been adding Direct Injection to some of their higher end vehicles yielding an additional 15% in HP while maintaining fuel economy. Now take the current 155 HP engine, add 15% and you have about 178 HP. Now, create two new smaller engines based on this design for smaller vehicles:
(the current Cobalt is a 2800 lb car). So if you reduce the engine size by 18% and 27% and do the same for the weight of two newer models, say 2300 and 2050 you will wind up with a 145HP, 1.8L engine and 130 HP, 1.6L engine. And the numbers in fuel economy would be even better than the Cobalt, with the 1.6L approaching the new Cruze’s MPG.

Think these HP figures are a stretch???? Think again, Chrysler currently has a 1.8L for sale in the US that makes 148 HP!!!!

I know that GM makes an Aveo with a 1.4 L with about 90 – 100 HP and a 1.2 with about 82 HP for other markets.

Instead, GM spends money developing a totally new engine (will the turbo last?) versus enhancing an already good idea. Yes, I agree that a new vehicle is needed…..

bottom line though, a car with 2/3 the displacement is likely to use less gas, even still when coupled to the turbo.

Because they are too ashamed of the poor reliability of their cars in general.

You may want to take a lesson yourself.. They use the exhaust gases to spin a fan, which forces more fresh air into the combustion chamber via another fan. Same principle as a blower, but the blower does this off a belt drive. A turbo does not recirculate the exhaust gases, it uses one fan to turn another on the same shaft. The “lag” is due to the fact that the exhaust gases do not spin up the turbo instantaneously, it takes a moment to catch up. A turbo can also inadvertently heat the air it sends to the combustion chamber, which produces a less effective mixture. Which is why many turbos have some type of cooling mechanism for the fresh air intake.

You say the supercharger is bad because “more air is sent to the engine”. A turbo does the exact same thing. And when you increase the air pressure, you gotta increase the fuel.