Do you care about the gas mileage you get?

[sportyaccordy]

Yes, one can sky high non-DI compression ratios with street gas providing the proper cam is used (tons over overlap). And actually, the sky high CRs are needed to support the huge cam, not the other way around. The caveat is these motors run like total dogs at lower RPM as all that overlap results in a very low effective CR at lower engine speeds.

One can do super high compression + a normalish cam if they play with ignition timing & optimize the combustion chamber. Minimize hot spots, retard timing a bit, engine will run great.

[SVT_Power]

Of course, with 12:1 you'll need to run super premium grade fuel, or possibly mix a little race gas or octane boost to keep it from detonating.

We have an old (2000) Silverado that was converted to tri-fuel use back in the day for a AVTC that was designed to run on propane, ethanol, and gasoline. I believe the compression ratio is 13:1 and it runs okay with 94 octane pump gas.

[Raza]

Yeah.  Consistent speed on the highway, using clean air whenever you can, staying around 70-80.  On surface streets I don't really give a shit, but I do 15,000+ on the highway a year (down from 25,000+).  I can always use an extra thousand dollars spent on something I'd rather be doing than gassing up.  And there's the time.  Nothing like getting out of work 5 minutes early to waste 10 minutes fueling up because you don't have enough gas to make it home.  I don't sacrifice fun, but there's little fun to be had on a highway anyway. 

[GoCougs]

One can do super high compression + a normalish cam if they play with ignition timing & optimize the combustion chamber. Minimize hot spots, retard timing a bit, engine will run great.

If it were that easy automakers would've done that a long time ago as higher CR = higher efficiency = better MPG. Retarding timing kills power and knowing how/where to minimize hot spots in the combustion chamber is not something a shade tree mechanic can do.

[r0tor]

I track my mpg on both my gas hogs and actually drive pretty conservatively around town and on the highway in both.  I just don't see the reason to romp on the gas in town when the next redlight is looking at you not too far away.

When i get on the back roads all that goes out the window... Especially in the Mazda

[hotrodalex]

Yes, one can sky high non-DI compression ratios with street gas providing the proper cam is used (tons over overlap). And actually, the sky high CRs are needed to support the huge cam, not the other way around. The caveat is these motors run like total dogs at lower RPM as all that overlap results in a very low effective CR at lower engine speeds.

VTAK, yo. (VTAK compression ratio as well? )

[Morris Minor]

I don't really care. I'm lucky enough to be able to pay the bills without sweat.

[FoMoJo]

There was a time that I didn't but now I do.  Driving fast is no longer a thrill for me but driving efficiently gives me satisfaction.  I, recently, drove to Ottawa and back, about 650 Kilometres, and averaged 6.666... litres per 100 kilometres - about 35 miles per US gallon - in my wife's '09 Escape.  I was pleasantly surprised. 

[shp4man]

Ok, this is the downside to the pickup. It's averaging about 14-15 MPG, so ya, I do care.The Bug did about 26 MPG. But the Harley gets 45- It gets 42 even when I thrash it. So I guess WTF?  

[Galaxy]

There was a time that I didn't but now I do.  Driving fast is no longer a thrill for me but driving efficiently gives me satisfaction.  I, recently, drove to Ottawa and back, about 650 Kilometres, and averaged 6.666... litres per 100 kilometres - about 35 miles per US gallon - in my wife's '09 Escape.  I was pleasantly surprised. 

Ahh, so you are the target market for cars that grow flowers on the dash display to reward efficient driving. 

[Byteme]

There was a time that I didn't but now I do.  Driving fast is no longer a thrill for me but driving efficiently gives me satisfaction.  I, recently, drove to Ottawa and back, about 650 Kilometres, and averaged 6.666... litres per 100 kilometres - about 35 miles per US gallon - in my wife's '09 Escape.  I was pleasantly surprised. 

35 is decent indeed.  I don't think I ever got over 30 in my 5 speed 4 cyl 2001 model.  Blame a lead foot and the aerodynamics of a tissue box.

[FoMoJo]

Ahh, so you are the target market for cars that grow flowers on the dash display to reward efficient driving. 

That would be cool .

[FoMoJo]

35 is decent indeed.  I don't think I ever got over 30 in my 5 speed 4 cyl 2001 model.  Blame a lead foot and the aerodynamics of a tissue box.

The 2.5 litre engine, I believe, is quite an improvement over the old 2.0 litre.  As well, the 6 spd. auto is mapped for efficiency.

Typically, it doesn't do quite as well.  However, it was a mild, windless day with very little traffic on a Provincial highway with an 80 kph speed limit.  I set the cruise for 90 kph (55 mph) and seldom had to vary speed; except for the occasional small town.  Ideal conditions.  Still, I was impressed.

[MexicoCityM3]

I do find it fun sometimes to drive efficiently and see how low can I go on fuel consumption. Usually after a fill up. However, inevitably I will floor it sometime before eating up a tank and afger that it is all downhill till the next fill-up.

When tracking I will sometimes reset the mileage computer when I get to the track and then again after I leave to "compare" maximum to minimum fuel consumption. It is easily more than a 100% difference.

[Raza]

I do find it fun sometimes to drive efficiently and see how low can I go on fuel consumption. Usually after a fill up. However, inevitably I will floor it sometime before eating up a tank and afger that it is all downhill till the next fill-up.

When tracking I will sometimes reset the mileage computer when I get to the track and then again after I leave to "compare" maximum to minimum fuel consumption. It is easily more than a 100% difference.

Fun isn't the word I'd use...interesting, perhaps. 

[Onslaught]

Fun isn't the word I'd use...interesting, perhaps. 

I had fun with it one time. I wanted to see if I could get over 300 miles out of one tank of gas in the RX-8. After doing it I never gave it a try again.

[CALL_911]

Fun isn't the word I'd use...interesting, perhaps. 

+1

Although I play that game all the fucking time.

[Soup DeVille]

I had fun with it one time. I wanted to see if I could get over 300 miles out of one tank of gas in the RX-8. After doing it I never gave it a try again.

Ever wonder why most cars have a near 300 mile range?

[Rupert]

I have a theoretical 520 mile range in the 944.

[Raza]

Ever wonder why most cars have a near 300 mile range?

I always thought they built the gas tank capacity around a theoretical 400 mile range. 

[Soup DeVille]

I always thought they built the gas tank capacity around a theoretical 400 mile range. 

It was based on the distance between Detroit and Chicago.

[Secret Chimp]

In my Miata, no. In my Dodge, yes, as it's indicated if I've fixed whatever's going on with it yet or not. If I can ever get it up to the original 17-21 it was supposed to get I'll actually be able to go on trips without worrying about going broke.

[565]

Some of my cars are effected more by driving styles than others.  In the pathfinder it doesn't matter if I drive like a hooligan or a grandpa, I always get around 17 MPG, probably because it's got so little hp (168)  moving so much mass (4000+ lbs) that driving it like a madman doesn't make it move any faster.  That said it's the same for the Supra, the gas mileage doesn't seem to change no matter how I drive it, around 19MPG. The car cruises at well over 3000rpm on the highway.  The Z06 has ranged between like 10-11 mpg to around 30mpg depending on how I drive it.

[Onslaught]

It was based on the distance between Detroit and Chicago.

You could do it in the RX-8. But you'll be pushing it.

[Vinsanity]

I always thought they built the gas tank capacity around a theoretical 400 mile range. 

It was based on the distance between Detroit and Chicago.

My car is a classic example of that. 25 mpg highway * 16 gallon fuel tank = 400 mile range

[Rupert]

29 highway, 19-ish gallon tank.

[dazzleman]

My car is a classic example of that. 25 mpg highway * 16 gallon fuel tank = 400 mile range

You drive a CTS, right?

How fast do you go on the highway to get 25 mpg?  Is your mileage affected by speed?  I get the sense that the whole logic for the 55 mph speed limit back in the 1970s -- that 55 mph is the optimal speed for gas mileage -- doesn't hold true in today's cars, and that the optimal speed for most cars could be somewhat higher.

[Rupert]

Eh, I dunno. 55 seems to work well, in terms of mileage.

[dazzleman]

Eh, I dunno. 55 seems to work well, in terms of mileage.

I haven't done a real study, but I don't think my mileage starts to really suffer until I'm over 70 mph or so.  But you may be right.  I haven't really studied it; what I said was just a hunch.

[CALL_911]

I haven't done a real study, but I don't think my mileage starts to really suffer until I'm over 70 mph or so.  But you may be right.  I haven't really studied it; what I said was just a hunch.

My dad claims he gets his best mileage at about 70-75. From there it's downhill.