I burned 160L of deisel and 80L of gas...

[MazdaMatt]

...All between last thursday and this monday.

2 hours in my Mazda Protege from home to pick up my truck
6 hours to the race track in my truck
A few sessions at the race track
4.5 hours in the truck to my parent's house
2 hours back to where i keep my truck
2 hours in my mazda back home.

Truck - 160L of Deisel
Mazda - 40L of gas
Race car - 40L of gas

The crazy part is... i was trying to use as little gas as possible.

This truck is rediculous. I managed to pull off 19.5L/100km (12.5MPG). I Drove 85-90km/h on the freeway (100km/h zone, 120 standard traffic speed). I drove 70-80km/h highways (80km/h zone). I maintained 70 in the 60 zones to stay in top gear and 40 in the 50 zones to stay at low rpms. I tried to stay behind trucks on the freeway. I slowed down for uphills and sped up for downhills. I tried 2 neutral coasts and my tranny made horrible noises for the next hour when i was near the 3-2 downshift speeds. Is 12.5MPG that bad for a 5000lb truck with a 7.3L deisel and a 3-speed city-designed transmission?

The race car is a honda... 1.6L and has the fuel efficient gear ratios... bad for speed. I use as much gas in a day as the vette guys use in a single track session. I only left it idling once because i ran for 10 minutes with the temp guage pegged to the red (I had to cut open my bumper to make it run cooler after I put on an air dam)

The mazda I drove at 100km/h on the freeway, stayed behind trucks, pulse/glide where possible, coast down hills...

So... fire away... I can take it.

[bikin' Ed]

Matt, I'm no expert, but I thought that diesels were supposed to get much higher FE. Chevrolet is advertising 20 mpg for their full sized 1/2 ton silverado V-8 gasoline. I's sure the diesel pros will give you the advice you need.

[MazdaMatt]

Hehe... let me elaborate on the truck.

F350 7.3L non-turbo V8 with a 3-speed tranny, shifts into top gear at 65km/h. It has a TWENTY foot long, 8 foot high, 8 foot wide enclosed box and it contains my 2100 pound race car as well as spare tires, tools, a queen sized bed, gas, etc

[MazdaMatt]

... it IS aero modded with one of those nose-bubbles on the cube above the cab. However, the things is so un-aero that in the rain there is NO movement of water along the hood and the rain hits the windshield and has no sideways movement at all, it just has a huge stale air pocket. That's why i drive so much under the limit...

I did a rough-estimate test and found that driving a trip at 110km/h used DOUBLE the gas that driving the same trip at 85-90km/h used.

[mavinwy]

Actually, for what it is....That is pretty good mileage.....

Jim

[MazdaMatt]

It is getting a service next week before my next trip. The next trip is to a track that is 2 hours closer, so only 8 hours in the truck instead of 12.5 (also no detour to parents). Apparently one of the rear brakes is stuck so it is probably rubbing and it will be getting an oil change. I'll see if it needs an air filter, but i think that is newish.

What are the throttle tips for deisel driving? I can't possibly drive with my foot in one position to slow down uphill and speed up downhill... the slightest grade in the road requires added throttle just to maintain top gear when i've been maintaining 80 and i barely speed up on the downhills because not adding throttle means the engine won't spin up much and the locked TC causes engine braking.

What I've been doign is gradually getting into the throttle for accel, staying "just ahead of the engine"... ie, i don't floor it from a stop, i give it a little more gas than it needs to stay steady. I let the speed come WAY down for hills without letting it downshift.

[IndyIan]

Could you store your truck closer to you?
Also maybe look into a trailer? A couple guys that do solo 2 with me have very low flat bed trailers with a tirerack up front and lockable box. There are a few trucks that would tow that setup and still get very close to your mazda 3 in mileage for daily driver use. A V6 tracker/XL7 if you need 4x4 or a 2wd Ranger might do it too. I don't know what the tow rating is for a 4 banger ranger but guys here do well with them. They can't be any slower than your truck even with 4000lbs behind them.

Also was fuel even your biggest expense for the weekend? I'd love to get a cheap race car and bomb around but I don't have the cash or permission to spend it if I had it...

[MazdaMatt]

Cheapest way to go racing... 1000 for a civic, 500 for a pre-bent/cut cage install it yourself. 100 for a used racing seat, 50 for a harness, 400 for tires. Reduce the weight and go! Gas was not my largest expense, but that is only because i was running a very expensive track. btw, i run time trials, not head to head... you need to spend more on safety gear for head to head, but you don't even need a cage or seat/harness for time trials.

I've used a tow dolly and a ranger and it was not good at all... that was a small v6 range 4wd offroad package. I rather enjoy having my car parked inside my truck and having a bed in there and a lock on it to have everything secure and dry inside. I definately have been toying with the idea of selling my truck and my car and buying a pickup and a trailer, but i need to find the right combo for me.

My truck is 2 hours away, yes, but it is in the right direction

[MazdaMatt]

wow... this thread came back from the dead. If you can't get >12mpg in anything smaller than my 6000lb 20ft cube van with an injector leak, you shouldn't be driving a car.