Here's a more complete EPA list of the new 2005 vehicles....probably substract ~10% for real world numbers. 2005 Model Year Fuel Economy Leaders MPG Rank Manufacturer/Model city/highway 1. Honda Insight (hybrid-electric, manual) 61/66 2. Toyota Prius (hybrid-electric) 60/51 3. Honda Insight (hybrid-electric, automatic) 57/56 4. Honda Civic Hybrid (automatic, lean burn) 48/47 5. Honda Civic Hybrid (automatic) 47/48 6. Honda Civic Hybrid (manual, lean burn) 46/51 7. Honda Civic Hybrid (manual) 45/51 8. Volkswagen New Beetle/Golf/Jetta (diesel, manual) 38/46 9. Volkswagen Jetta Wagon (diesel, manual) 36/47 10. Honda Civic (manual) 36/44 Highest Fuel Economy by Vehicle Class 2005 Model Year MPG Class Model city/highway Two Seater Honda Insight (manual) 61/66 Minicompact Car Mini Cooper (manual 5-speed) 28/36 Subcompact Car Volkswagen New Beetle Diesel (man.) 38/46 Compact Car Honda Civic Hybrid (automatic, "lean burn") 48/47 Midsize Car Toyota Prius (hybrid) 60/51 Large Car Chevrolet Malibu Maxx 22/30 Small Station Wagon Volkswagen Jetta Wagon Diesel (manual) 36/47 Midsize Station Wagon Passat Diesel Wagon 27/38 Sport Utility Vehicle Ford Escape HEV (2WD) 36/31 Minivan Honda Odyssey 20/28 Pickup Truck Ford Ranger Pickup 2WD 24/29 Mazda B2300 2WD Cargo Van Chevrolet Astro 2WD (Cargo) 16/22 GMC Safari 2WD (Cargo) * Passenger Van Chevrolet Astro 2WD (Passenger) 16/21 GMC Safari 2WD (Passenger) Lowest Fuel Economy Models* 2005 Model Year MPG Rank Manufacturer/Model city/highway 1. Dodge Ram Pickup 2WD (automatic) 9/12 2. Lamborghini L-147/148 Murcielago (manual) 9/13 3. Dodge Ram Pickup 2WD (manual) 9/15 Lamborghini L-140/141 Gallardo (automatic) " 4. Bentley Arnage, Arnage LWB 10/14 5. Lamborghini L-147/148 Murcielago (automatic) 10/15 6. Ferrari 360 Modena/Spider/Challenge (automatic) 10/16 Ferrari 575 M Maranello (manual) " 7. Ferrari 575 M Maranello (automatic-3mode) 10/17 Ferrari 612 Scaglietti (automatic) " Lamborghini L-140/141 Gallardo " 8. Ferrari 360 Modena/Spider/Challenge (manual) 11/16 9. Ferrari 612 Scaglietti (manual) 11/17 10. Bentley Continental GT (automatic) 11/18 Aston Martin DB9 Volante (automatic) " *Trucks over 8500 pounds gross vehicle weight rating are exempt from federal fuel economy requirements. Lowest Fuel Economy by Vehicle Class* 2005 Model Year MPG Class Make/Model city/highway Two Seater Lamborghini L-147/148 Murcielago 9/13 Minicompact Car Aston Martin DB9 Volante 11/18 Subcompact Car Maserati Coupe & Gransport 12/17 Compact Car Bentley Continental GT 11/18 Midsize Car Bentley Arnage 10/14 Large Car Bentley Arnage LWB 10/14 Small Station Wagon Audi S4 Avant (manual) 15/21 Midsize Station Wagon Mercedes E55 AMG Wagon 14/21 Sport Utility Vehicle Mercedes G55 AMG 12/14 Minivan Kia Sedona 16/22 Pickup Truck Dodge Ram 1500 Pickup 2WD 9/12 Cargo Van Chevrolet Astro AWD (Cargo) Conv 14/17 GMC Safari AWD (Cargo) Conv " Ford E150 Econoline 2WD " Passenger Van Ford E150 Club Wagon 13/17

Yep, a leak I put a 10 oz can in last July 3, and the system worked fine all the rest of that summer. That time the A/C was just low, not "too low" and it was still cooling, just not as much as it should. The additional (without gauge) refrigerant brought the delta Temp up to specs. The trouble shooting of no clutch engagement led me to just add another 10 oz can to see what happens. The engine was running with the A/C switch "on" and it took only 10 seconds of the fill (these cans can take up to 10 minutes to empty on a nearly full system) for the clutch to engage and about 3 or 4 minutes to empty the can. I'll let it run this way for a few days and see what happens (it is cool here in NJ right now - in low 40s this morning). If it holds for a week I'll just top off using a guage and some anti leak. If I can get the car through the hot weather of 2013 for under $50 invested, I'll take it and worry abvut next summer if the car and I are both still around. Both of "us" are Senior Citizens. Up to 2009 I had always taken my purchased new cars to a shop to have the A/C serviced. I have kept all cars purchased new for at least 10 years, the 2004 is obviously coming up on 10 years - so new car is on the possible solution list. A 1999 Mazda was my first time adding refrigerant myself, it worked out fine there too - also just added a can to increase cooling, and it worked. I traded that car in before much of a test on the pump-up, but I did keep that car through that summer that I added the refrigerant.

" but the center spark plug arrangement would be a nice "geometry" in my mind/eye - does that have anything to do with the spark plug placement? " Oh yes indeedy! When Chrysler designed its hemispherical head, they put the spark plug in the top center of the combustion chamber. The downside was that you had to go through the valve cover to get to the plugs. This necessitated adding a plug tube and sealing it at both ends, in other words, extra parts and places to seep oil, and extra cost. During the '50s through 80s, this design was avoided in many engines, and plugs sprouted from the sides of the heads. At one time, I had a 400 CID V8 with the plugs under the exhaust manifold. I had to crawl under the car to change number 7 and 8 plugs. I got a frost bite burn one winter doing this. It became painfully obvious in the '70s that the kluge fixes to meet cleaner exhausts was not a permanent solution. Engine output fell during this period and in many cases, efficiency fell too. To track what the Japanese engine makers were doing, look at their motocycle engines. Many things were tried on these engines and the sucessful stuff got incroporated into their automotive engines about 2 years after a success in a motocycle engine. Multiple valves was sold in cycle engines before these appeared in cars. Yahama was up to 5 valves per cylinder, 3 intakes and 2 exhausts, before settling to 4 valves per cylinder. Today, many car engines can be found with 4 valves per cylinder as a means to boost the breathing of small displacement engiines. Next came a pair of counter rotating weights spinning at twice engine speed to take a lot of the "buzzies" out of the 4 cylined engine. These first appeared in cycle engines, then car engines. There is one precaution one should take with spark plugs down a tube, or for that matter, any sparkplug, and that is to prevent debris from entering the cylinder when the plug is removed. If you have an air supply, its a good idea to blow out any loose stuff before removing the plug. When the plug is in a hole, shine a light down there and look for any liquid that might be lurking there. If you see any, sop it out before plug removal, because that liquid will drain into the cylinder when the plug is removed and can cause problems on startup if too much is in the cylinder. If there is any junk in the fluid that can poison the catalytic converter, it will, although the likelehood of this is small.

Without hearing the noise myself, I can't tell what it might be. There are so many possiblities. I will list a few below: 1. Badly worn ball joint. 2. Dry joints needing lube. 3. Loose steering box bolts. 4. Loose and dry wheel bearing. 5. Brake parts. 6. Wheel cover (hub cap). A weak or cracked rim can flex enough to cause a 'scrunching' noise from a poorly fitting (metal) wheel cover. Once, I had such a wheel cover and did not discover the noise source until one day while driving with the window open and passing a short wall, I head the sound reflecting off the wall. One of the friction tangs on the wheel cover was scraping back and forth as the wheel rotated and flexed. 7. Separated engine mount. 8. Dry shaft at rear of transmission. This splined shaft is supposed to be lubed to allow a small amount of sliding of the drive shaft. 9. Worn out holes around the lug nuts. Dryed out steering damper. ( This is a samll shock absorber fastened to the steering rods.) Let us know what you find. You may need an observer standing outside the truck while you produce the noise.