8.5 mpg city? or about 120 miles per tank city?

[Kirkinsb]

I get about 120 miles out of a tank of gas. And I really don't drive all that aggressive. I have an SCT Tune and wonder if it is running really rich and burning lots of fuel. I guess the car exhaust does not smell funny nor do I have any other signs that something is wrong. More wondering if my tune is way off. Might throw the stock tune back in and drive for a while.

Thoughts?

 

[MoparMap]

What sort of city driving do you do? Is it really congested or moderately open with just stop lights/signs? I get around 18 with my commute that's probably 60/40 highway/city, but I think the worst I've ever gotten with a lot of town driving was probably still 12 or better. Sounds like something might be a little off, but I'd expect a noticeable smell. Do you still have the cats on the car? I suppose that could mask the smell. I just had to get rid of mine when I put on headers and can notice the smell at idle, but it's not overpowering. There's a touch of black smoke on a hard accel hit, but I haven't had my SCT tune updated after the header swap.

 

[Morketh]

I did a 120 mile round trip on a little less than half a tank with about 70% highway and 30% city.
2006 coupe

 

[NMviperguy]

Just finished my first in city tank. Mine is bone stock and I averaged 18mpg... With an extremely heavy foot... Still getting s feel for the power, and havent turned down a race yet... Guess there is something about taking out a brand new 2015 mustang gt or roush that says... My 11 year old car is better than yours. I'd say 50/50 highway/city, but I spend a lot of time in 6th gear even if in the city as long as I'm over 50mph... Still better mileage than my girlfriends escalade

 

[Kirkinsb]

100% City driving. Mostly stop and go with very little time at constant throttle. Also very short trips. My engine hardly has time to fully warm up! My work is only 3 miles from home....so lots of 3 mile trips each day. I have my CATS removed as well. I think I will try my stock tune for a tank and see. It just seems off. My BUTT dyno did not seem to pick up any extra HP when I did the new tune. But I know the tune went in because my skip-shift eliminator setting worked.

I will get my car over to the dyno and really see what is going on soon and post it. My guess is the tune is really rich.

 

[Dom426h]

I dont think the tune is your problem.

Attempting to make sense of City mpg is a waste of time IMO. It is not easy to realisticly compare to others as one persons definition of "city driving" could be a light every 1/8-1/4mile or so with minimal traffic as where anothers could be stop and go traffic block by block in rushhour.

It is easy for any large displacement motor to go less than 10mpg in congested stop & go city driving.

If you really want to know if something is up with your viper then i suggest going for a roadtrip on the freeway and averaging 60-75 mph in 6th gear. If you see 17-22 mpg then all is good.

Also, not sure how your measuring but the proper way is to:
1. fill-up
2. 0 the odo trip
3. Drive till less than half tank (preferably as close to empty as possible though)
4. Fill-up and note the exact amount of fuel put in.
5. Use a calculator to divide:
miles driven / fuel used

 

[NMviperguy]

^agreed! This is the same method I used

 

[Nsane1]

That sounds pretty low for "normal" city driving. What I would do, is go to an event that's a cruise, and fill up with everyone else and see where you sit during the route.

I did this and it pointed to a really jacked up rear end as I was getting literally 30% less miles than everyone else.

 

[Kirkinsb]

Yep, I calculate MPG this way as shown below. I went 120 miles on 14.3 gallons of gas. worked out to 8.4mpg. Low fuel light came on, so I drove it very close to empty. Maybe all is OK, and like Dom426h says..it is a waste of time to try and compare as there are so many variables. Again, I am not worried about MPG as much as if my tune is off. I need to schedule an appointment to the dyno to solve it once and for all. I will get that scheduled. I will do a run without the tune and then load the tune up and do one with. Thanks all.

1. fill-up
2. 0 the odo trip
3. Drive till less than half tank (preferably as close to empty as possible though)
4. Fill-up and note the exact amount of fuel put in.
5. Use a calculator to divide:
miles driven / fuel used

 

[Paul Hawker]

Count yourself lucky. In my 96, I only got 2.2 mpg....At Buttonwillow race track : >)

Had to refuel at lunchtime.

 

[Allan]

Count yourself lucky. In my 96, I only got 2.2 mpg....At Buttonwillow race track : >)

Had to refuel at lunchtime.

I always have to fill up at lunchtime too.

I don't give a crap about the miles.......................



All I care about is the SMILES.

 

[Kirkinsb]

I threw my stock tune back in tonight and it feels more crisp if that makes any sense. There is much less backfiring on decel and it seems to run really well. I think my canned tune is way off. I will dyno back to back and find out what is going on and which one has the best power curve/top end. I really don't care much about mileage either...just want my car to run the best it can.

 

[NMviperguy]

Agreed... Don't think any of us got a v10 for Prius numbers... Although the hybrid motors Ferrari and Porsche are working on would be interesting on newer vipers....

 

[Kirkinsb]

Ok, ran a tank through with the stock tune versus the SCT Tune. Pretty much drove it the exact same. It went from 8.5 to 11 mpg. Could a tune really make it loose that many mpg without any seat of the pants gains? I need to get to the dyno for some conclusive results....but for now, the stock tune feels better. Are SCT tunes on a basically stock viper running 91 octane simply not worth it? iF yes, I have a basically new SCT tuner for sale!!! ha.

 

[MoparMap]

My car just had a filter and catback when I bought it and a tune (at least that's what I've been told) and it ran pretty strong on dyno day. Put down 480/530 hp/tq. I think there are gains to be had, but every engine is different too. Ran the exact same combo the next year and was down almost 50 ft-lbs, so I think something was up with the system. Either I was slipping on the rollers or there was something funny going on in the tune. I know I had a cracked plug wire when I installed my headers, but I think I cracked it during the install and not before, but I suppose maybe it was on the way out. Either way, will see what it does this year and if it can match the first time's numbers again.