I once filled up in Cornwall Ontario and drove 1,154 km to Fredricton New Brunswick on a tank of gas, how many people can get over 1,154 km on one tankful? Okay so it was in a Suburban with 170 litre tank.....But that's still close to 7litres / 100km. We were on holidays so I went for mileage just for fun.

Seriously though I posted this in another thread, my Cadillac's on board computer has made me very consience about driving habits and my runs to the cottage now become a compromise between fuel econmy and driving just slow enough not to be run over on Hwy 400 where the average speed (for those not in Ontario) is about 140 kph. I use the neutral trick all the time but with it's shear mass the Caddy get's going pretty darn fast, I only use the brakes when necessary and I have found that about 116 kph is safe enough to drive on the 400 so that's where I peg the cruise, any higher than that and the fuel consumption starts dipping. I also run 40 PSI all round. Even at this my last trip was 8.5 litres / 100 km. I suppose you can't expect much better from a 32 valve, dual over head cam 275 HP motor.

Todd, that is interesting that you get about 23. I drive my 6 speed LT1 94 Impala SS about 7 miles each way to work. It's all country driving, no town traffic. It does about 23mpg in the summer!

On the open road, it will do about 27. People ask me how I can afford to drive a gas hog. When I tell them I'm likely doing better on fuel than their van, or in some case their FWD car they are amazed.

Our Roadmaster has pulled off 30 mpg on an interstate run from here to Minneapolis (400 miles) driving 70 mph, no a/c on, no stops. Again, why drive a small car???

I posted the politically correct litres / 100 km. To be consistent with the others, my Cadillac is getting 25-27 highway and 15 - 17 city. At some point power to weight ratio has to come into effect combined with gearing on these big V8 cars. Another thing to consider is how many passengers you can accomodate in a big car versus taking two small cars on the same trip to accomodate people and luggage. Lastly I am 6'2" and although I have not stepped on a scale lately I am 250 lbs. at least....small cars don't fit me!

Carl Stevenson wrote:

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Isn't it funny that the higher horse LT1's are better than the throttle body engines? We had a 92 Roadmaster sedan with a 350 prior to this car, and this one has about 60 more horsepower and better fuel economy. Go figure.

To me the LT1 and the 3800 are the two best mileage engines out there for the power they return.

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This is my point exactly on power to weight. Ironic too that both engines initially introduced in the 50's and early 60's are among two of GM's best, now out of production.....go figure.