fuel, does it add to the cars total weight?

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Epinionator89
Finally, I have completed the test. I drove 354.5 miles before the test car, a 2002 Mitsubishi Colt (stock) ran out of gas. Here are the results:

Tank Amt.---0-60MPH-----Lap Time
Full-----------11.75 sec.---3'19'304
Half-----------11.55 sec.---3'19'027
Emply (1 bar)--11.24 sec.---3'18'590


Conclusion: It might be due to break-in, but there's definitely something behind the gas weight theory. I shaved .51 seconds off my 0-60 time, and nearly one second on my lap time. The entire test took 3 hours, 6 minutes and 46.423 seconds.

Most driving was done by the B-Spec driver on the #5 setting since he/she was only used to burn fuel during the times I didn't need testing.

Zero-to-sixty times were done by me when the clock timer reached ten seconds (0'10'000), and recorded once the car reached sixty miles per hour and the screen was paused.

Lap times were done immediately after the zero-to-sixty test by finishing the lap done for it and doing one more. The latter lap was recorded since starting and finishing speed were the same. If recording the former lap (the one used to help record 0-60 times), the times would obviously be skewed.

Things to work on next: Try a car already broken in, with no modifications except for an oil change beforehand. This might be best done with a used car, but a refresh would be neccesary as well. I feel there should be more testing before coming to a fully, unquestionably accurate conclusion.
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I have thought of this before and been thinking if it is true. Good job Epinionator89 you have answered the topic of this thread.
 
Supren
Good job Epinionator89 you have answered the topic of this thread.
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Hmmmm, not necessarily.

I think that further testing is needed and since you have an affinity with watching paint dry, you might be just the man for the job. Perhaps this time use a car where a change in power/weight ratio will have a bigger effect. I was thinking along the lines of a formula 1 as stated previously in the thread. This way when the tank is empty it should have a greater effect on the car's overall weight (percentage wise). I think something like this will yield a greater gap in results if the theory proves true. Or you could use something like a Caterham or the Ginetta, as they are very light as well and full tank to empty tank will have a larger effect.

Feel free to go forth and test... :)
 
For the mielage debacle, you also have to take into account engine type (not neccesarily size) and car weight. For example, the dedicated hybrids, Prius sedans (and maybe the Honda Insight) don't use fuel at all, which really doesn't make any since at all. The 2 diesels (the Lupo 1.4 and BMW 120D) also don't use that much fuel. Today I plan on doing a comparison of the amount of laps able to be taken on test course between the 120D and the 120i. The big engined heavy petrol cars use gas like it's going out of style (like the Mercedes SL 600 of Chevy Chevelle SS454), yet the Viper, even with it's 500 cubic inch engine, is fairly light and therefore doesn't use fuel . Explaining the rather surprisingly large apparent fuel mileage of the Tank Car, PD probably modeled the units system around the real life size and holding capacity of the fuel tank, and considering the size of the engine, it's only logical that it has a huge gas tank. I'm also pondering whether wind resistance from spoiler and high Cd's effect mileage. I'm not sure of a way to prove that, however.
 
Toronado
I'm also pondering whether wind resistance from spoiler and high Cd's effect mileage. I'm not sure of a way to prove that, however.
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You could take a car with massive adjustable downforce, Formula One again, and run some laps with max downforce, and some laps with min downforce. That'd be a good start, but not sure about drag co-efficients though... :)
 
I do think there is a difference in tank size. example. CLK LM after 2 stints on tokyo R246 (the GTWC race) will be on fumes with less than 5 units in the tank. The XJR-9 is only sitting just under a half tank. I know that most modern LM cars run an 80-90L tank. The old group C cars could run a much bigger tank (140L i think). And I gaurntee a 975hp group C car is going to use more fuel than a modern LM car
 
ferrari_chris
You could take a car with massive adjustable downforce, Formula One again, and run some laps with max downforce, and some laps with min downforce. That'd be a good start, but not sure about drag co-efficients though... :)
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Thanks for the help. I have figured out a way! The Honda Oddesey and the Honda Element have the exact same engines...and they are in no way shaped similar...
 
Okay, here is my expririment. I am testing to see whether or not the engine type changes anything in GT4. The car: BMW 120 D with a spoiler for the next test (wind resistance from spoiler). Down force off. B-Spec set to 5. For trial 2: BMW 120 i with the same spoiler (just in case that would do anything) and downforce also set to off. B-Spec set to 5. Every 30 mintues I will check the fuel bars and have it litterally run out of gas on the track. I willl then exit and check how many miles the car ran before running out of gas. I will do the same for the 120 i.

Results: After one 30 minute period, the 120 D has lost 3 fuel bars after driving at a steady pace of 139/140 MHP.
After a 2nd 30 minute stint, the car has now lost total fuel bars but it's top speed has dropped to 139 MPH.
After 3rd 30 minute stint, the car has now only lost 2 fuel bars and is down to 2. It is running at around 138 MPH due to some unkown factor (possibly oil).
Final Results: The 120 d went for exactly 1:58:54 before running out of gas. The average speed fell from 140 MPH to 138 MHP. The best lap of 2:46.850 was completed in the end of the first 30 minutes and the total mileage was 274.8 miles.
 
Toronado
Okay, here is my expririment. I am testing to see whether or not the engine type changes anything in GT4....
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I'll run a supplemental test and re-run my Pescarolo with stock motor (sans stg. 3 Turbo). Since I already confirmed that running at a lower RPM and top speed consumes less fuel, I'm thinking this will save even more.
 
Now for the 120 i. It should be know the the power to wieght ratios and gearing are virtually identical so the only real unknown factor is tank size in real life.
After the first 30 minute stint, the 120 i is down 3 bars and is going a constant speed of 139 miles per hour. Basic Googling has told me that the gas tank on the 120i is 50 litres, or around 13.2 U.S. gallons.
After the 2nd 30 minute stint, the 120i has lost two bars and is travelling at a constant rate of 139 MPH, with me not believeing it ever hit 140 MPH.
Edit: Just to be nice to me, BMW made the tank on both cars the same capacity (50 litres, 13.2 gallons) so whatever car runs farther has better mileage.
After the 3rd stint, the 120 i is down to 2 bars of fuel, as the 120d was, but the 120i litteraly just went to 2 bars as I entered the room, whereas the 120d seems to have been there longer. The 120 i is travelling at a constant speed of 138 MPH.
The 120i not only bested the time distance of the 120d, but it's closing laps were faster. The 120i ran for 2:00:43 before running out of gas litteraly meters after crossing the finish line on the 44th lap. It's best lap was not as good, however. This tells me one of 4 things. 1, diesel to petrol fuel mileage was not implemented into GT4, which, if true, is a real shame. 2, I don't understand the geometry of diesels enough and are missing a key point (such as how diesels don't run good when revved or something). 3, This was a poor track to test fuel mileages on. 4, the 120i overcame it's disadvantage in power to weight ratio by it's measurable difference in weight (about 100 kg). I could use some opinions.
 
Hmm... difficult to say what this means about the size of the tank... I think at full tilt, both cars would be using a lot of fuel... so if we go by the 80 units as 80 liters reasoning, that puts consumption at around 5km/l, but if it were modelled after the stock tank of 50 liters, that would be around 8+ km/l... which might be optimistic considering you're going full bore at top speed... so I think the former would be true... (80 units in the pits = 80 liters), as 5 km/l is perfectly reasonable going full bore. That's what I get in my 2.0 MP3 when I'm really pushing it.

I think the deciding factor here is the inefficiency of the diesel at high rpms. Heck, if you're game enough, you could granny-drive the cars for a couple of laps then check their fuel consumption by going into the pits. Shift early, and try to level out at 2000rpm in top gear... won't have to be a long test, maybe just 15-20 minutes of driving each.
 
Funny thing is, I always seem to set my fastest laps on longer races (ie World Championship) when 've used up a lot of fuel. And I do these races on Super Hard racing tyres (R1) so I don't have to pit often.
 
Toronado
3, This was a poor track to test fuel mileages on.
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Why do you think this track wasn't good? I would have thought this was the best choice. Easy to get consistent times as there are less factors to cause any deviation such as hills, switchbacks and varying cambers.

A great test, and looking back I'm not surprised there's no diff. between diesel and petrol. It might be a bit optimistic to think that they'd create it to that level of detail, mind you they probably didn't expect anyone to carry out these tests either. :D
 
To put this clear:

Yes, fuel affects your car's total weight.

A simple test: Drive the 24h of La Sarthe in B-spec. (well not 24h but 1h or something). You'll see that the B-spec. driver at least goes 10 km/h faster when he's running out of fuel.
 
Epinionator89
Finally, I have completed the test. I drove 354.5 miles before the test car, a 2002 Mitsubishi Colt (stock) ran out of gas. Here are the results:

Tank Amt.---0-60MPH-----Lap Time
Full-----------11.75 sec.---3'19'304
Half-----------11.55 sec.---3'19'027
Emply (1 bar)--11.24 sec.---3'18'590
Click to expand...

your test has intregued me... i really like the methodology... but if you want to be really scientific about it, you'd have to find some way of removing your reaction time and other factors from the 0-60 testing.
as it stands, i think its not very scientific at all... i may do some testing of my own with some more sterility, as this issue of fuel intregues me.
things i would try to make it *better*

1. don't trust time... Would be better to use distance, as in: "stage" the car at the start/finish line and run up to the 1000m line, grab the top mph... if the fuel makes a difference it should be higher speed @ lower fuel level. when using time its very easy to get ~.5 seconds of "slop" in your figures just based on reaction times of hitting the gas and pause buttons... you're not a robot...

2. which brings me to this point, (i'm not sure if you did this or not) when doing drag trials of any scientific nature, it is very important to remove the human component as completely as possible. This can be achieved with the patented spieg "brick gas/AT" method. this consists of mashing a digital gas button and using the AT. no human needed... will replicate 400m times 100% of the time (if you make sure to put the brick on the gas while the track is loading)

3. when doing any scientific method, always remember to: rinse, lather, repeat!
if you only ran 3 "sort of" reliable 0-60 times, its no where near enough data to get any sort of conclustion from.


now that i've been thinking about all this... time and distance could be both used i think it would be best to run a quarter mile + 1000m, not just a 0-60... there is a sector time @ 400m and 1000m. could stage the car using the outside camera right before the finish line... then brick the gas and grab speed and time @ the split-traps... do that like 5 times in a row at full tank, 1/2 tank and empty tank and we'd have some good data.... i may just do this.
 

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