2014 Corvette Stingray - 30mpg hwy

[cujet]

Interestingly, my co-workers 1987 Corvette gets a real world 28 on the highway. 1MPG better than my 2.5L Jaguar X-Type/Ford with manual trans.

[oil pan 4]

The only way that Porsche is going to get 78mpg is if it comes with a fold up moped that goes in place of the spare tire.

[tjts1]

Read it and weep.
2015 Porsche 918 Spyder First Drive – Review – Car and Driver

[niky]

The 71 mpg is again, on the "New European Driving Cycle", which allows you to start the test with a full battery and end it with a flat one.

The EV-only range is in excess of the NEDC drive cycle, which is about 13km combined urban and extra-urban. That's how it gets such impressive figures. NEDC does force you to start with a cold engine, but the AC and other accessories are turned off.

This is quite inferior to the way the EPA does it, with multiple cycles and separate ratings for electric+gas and gas only. Gas only shows pure hybrid operation, with the batteries only charged from the onboard generator and brake energy recovery systems.

[Allch Chcar]

Originally Posted by UltArc

I think power comes into play, the 86 GT has less than half the HP of the Corvette, it should be seeing better than 32. 400+ gets 31, 180 gets 32?

34 MPG on the highway and 25 in the city for a car with 200BHP. The rating is for the AT but the MT gets about the same in the real world. The GT86 gets better MPG than the Corvette and it's almost half the price. We're not talking rocket surgery here. There isn't a direct relationship between MPG and HP.

[cujet]

Back to the economy thing...

One major factor in an engine's BSFC numbers is "piston ring swept area". As this swept area is 1) a major source, likely the biggest, source of friction, 2) an area for piston to cylinder heat transfer (wasting combustion heat) and engines with less swept area also have less surface area in the combustion area to transfer heat, boosting efficiency.

Engines with larger displacement spinning slower have significantly less piston ring swept area.

It's no surprise the large displacement V8 engine can achieve impressive economy in a lightweight, aerodynamic car. All it takes is proper tuning and proper gearing.

However, at idle, larger engines consume more fuel. And around town, this takes it's toll.

[UltArc]

Originally Posted by Allch Chcar

34 MPG on the highway and 25 in the city for a car with 200BHP. The rating is for the AT but the MT gets about the same in the real world. The GT86 gets better MPG than the Corvette and it's almost half the price. We're not talking rocket surgery here. There isn't a direct relationship between MPG and HP.

In an early page, one stated 30 mpg on the highway is not impressive for a sports car, and cited the 86 GT. I believe 34 mpg.

It's evident there isn't a direct relationship between MPG and HP, but having twice the horsepower, and almost 90% of the fuel economy, is impressive. I don't think anyone is talking about price, we're talking power to fuel economy- it's not the new Porsche, but it's also not a hybrid and it's less than a million.

[serialk11r]

Originally Posted by UltArc

It's evident there isn't a direct relationship between MPG and HP, but having twice the horsepower, and almost 90% of the fuel economy, is impressive. I don't think anyone is talking about price, we're talking power to fuel economy- it's not the new Porsche, but it's also not a hybrid and it's less than a million.

I think saying it has 90% of the fuel economy is a bit of an exaggeration. In the city when that giant V8 is idling and running at low load (even on 4 cylinders) it will suck much more fuel, that's a guarantee and it shows in the EPA city rating.

And if you want a more worldly Porsche to compare to, the new 981/991 s are pretty fuel efficient, have a good amount of horsepower, and don't cost 1 million.

[UltArc]

Originally Posted by serialk11r

I think saying it has 90% of the fuel economy is a bit of an exaggeration. In the city when that giant V8 is idling and running at low load (even on 4 cylinders) it will suck much more fuel, that's a guarantee and it shows in the EPA city rating.

And if you want a more worldly Porsche to compare to, the new 981/991 s are pretty fuel efficient, have a good amount of horsepower, and don't cost 1 million.

Agreed- but when one cuts their engine on the way to the light, it uses zero fuel

The point was highway, for this scenario-as I believe the OP intended.

http://ecomodder.com/forum/showthrea...tml#post381516

[tjts1]

EPA 45mpg combined in hybrid mode.
http://www.youtube.com/watch?feature...UB9RqY_I#t=594