How About That, 2014 Corvette Gets 37.3 mpg

[cbaber]

Originally Posted by serialk11r

Except the fuel economy isn't the same. I guess we should be talking about the Cayman S, with its 3.4L engine, to make things slightly more fair, but it's rated higher on the EPA than the Corvette.

But yes the fuel economy is surprisingly good on the Vette, but I wouldn't want to be caught in stop and go traffic with that 6.2L V8 :P Even in 4 cylinder mode I imagine that thing drinks more than its fair share of gasoline while idling.

We were originally comparing the 2.7 Cayman to the C7 because jamesqf claimed it could get 40 mpg at 70 mph. But the 2.7 and 3.4 Cayman S are rated the same (30 mpg) according to the Porsche website. C7 is 29 mpg, which is pretty much the same thing. The original conversation wasn't to compare the cars, but rather compare the engines.

I argued that the old school large displacement push rod V8 was actually an advantage for fuel economy vs a smaller displacement motor like the Cayman, because it produces more than 100 hp more than the Cayman S and nearly double the torque while still getting virtually the same highway fuel economy. The increased power without the increased thirst means 0-60 a half second faster than the Cayman S, which is also $10k+ more expensive than the C7.

[serialk11r]

Originally Posted by cbaber

We were originally comparing the 2.7 Cayman to the C7 because jamesqf claimed it could get 40 mpg at 70 mph. But the 2.7 and 3.4 Cayman S are rated the same (30 mpg) according to the Porsche website. C7 is 29 mpg, which is pretty much the same thing. The original conversation wasn't to compare the cars, but rather compare the engines.

Nah, I was the one who claimed the 40mpg. I said that because I drove a Cayman with a brand new engine (not broken in) and got 40mpg lol.

The 2.7 is rated 32 EPA, the 3.4 is rated 30, with slightly longer gearing. This is the PDK versions, which I think is fair because the C7 vette uses a 7 speed manual which Porsche only offers on the 911.

No doubt the cylinder deactivation helps, but the extra pistons it's lugging around definitely hurt the gas mileage. There is simply no way that a hypermiler would be capable of squeezing more mpg out of a C7 at lower speed than a Porsche driven by another hypermiler because the engine is just so big.

Freeway mpg is moot, the right gears means every car can get decent mpg. In the real world very few people get to drive all freeway miles, and the Cayman will whoop the Corvette in fuel economy off the freeway. If you want to talk horsepower to mpg ratio, the newer turbo engines do much much better, but again that's not relevant.

In my book the Porsche 9A1 engine is still better, because in its highest tuned state the 3.4 makes 350hp (the Cayman is limited to 325), and the X51 package on the 3.8 shows that you can easily increase the power of the 3.4L up to perhaps 380hp. This would not affect driveability the way fatter cams would on a Vette because they have a 2 stage lift system. If you really want to compare specific power, the 3.8L engine in 430hp form gives the LT1 a run for its money for sure, because it barely weighs any more than the 3.4, and Porsche could've given it the gearing to get 30mpg instead of 27. They don't use cylinder deactivation for smoothness reasons, but if they did the mpg would be even higher.

[oil pan 4]

Originally Posted by UltArc

Start stop will be coming- and they want eventual hybrid power trains. GM is on a good track, though many purists will surely be upset.

What do you mean "will be coming"?
Cars in Japan have had stop start for about 20 years.
GM, Ford, Toyota, Honda, Mitsu and everyone else knew that U.S. consumers would not be interested in or wouldn't understand why the vehicle keeps stopping in traffic.
Don't be fooled into thinking this is something new.

[UltArc]

It will be coming to the Corvette. Yes, I do know this is old technology for non sport/performance oriented vehicles.

[cRiPpLe_rOoStEr]

I don't consider the start-stop feature as a bad thing, but yes, it really may take some time until the average Joe gets used to it.

[oil pan 4]

The Japanese liked it because it was new, now its thought of as a standard feature.
Americans wont like it because its new and because when the engine is off so is the air conditioner.

[Xist]

Originally Posted by cRiPpLe_rOoStEr

I don't consider the start-stop feature as a bad thing, but yes, it really may take some time until the average Joe gets used to it.

I rented a Mercedes (the first car available) while I was in Germany and I did not realize that it had start-stop until was handing my ID to the Ponds gate guard.

Okay...

When he handed me my card back, I hit the accelerator, and the engine turned back on.

Cool.

Originally Posted by oil pan 4

The Japanese liked it because it was new, now its thought of as a standard feature.
Americans wont like it because its new and because when the engine is off so is the air conditioner.

Can you imagine?! They remote-start their car ten minutes before leaving only to realize that it turned itself back off, or they try to leave their engine idling and it turns itself off.

I have heard of towns that banned drive-throughs. Is start-stop inevitable? How much pollution would it really reduce?

[serialk11r]

Originally Posted by Xist

I have heard of towns that banned drive-throughs. Is start-stop inevitable? How much pollution would it really reduce?

It's worth recalling that start stop only kicks in after the engine is up to temperature (I think on Porsches it's ~140F oil temperature), so you wouldn't actually reduce pollution that much since start stop would only reduce idle emissions when the engine is running relatively clean.

The problem with start stop on American cars is that people here tend to be undereducated and will turn off the start stop because it's annoying. Kind of the same way people who drive stick will rev the nuts off their engine for no reason for "response" or perceived efficiency ("my engine is most efficient at 4000rpm! It's designed for it!).

[niky]

Originally Posted by oil pan 4

The Japanese liked it because it was new, now its thought of as a standard feature.
Americans wont like it because its new and because when the engine is off so is the air conditioner.

Depends.

The Mazda6 does it best, because it has a capacitor bank (which charges really, really fast) that can run the AC for a few minutes at a time.

In my driving, it meant a nearly 5 mpg difference in heavy traffic. (EPA, only 2 mpg). And the restart is smooth thanks to the cylinder priming system.

[oldtamiyaphile]

Originally Posted by oil pan 4

What do you mean "will be coming"?
Cars in Japan have had stop start for about 20 years.

I believe the Fiat Ritmo Strada was first in 1983.