Ok. I drove my new to me '83 300D (187K) for a longer while today to do a fuel mileage check.

IF my odometer is correct.......33.5mpg

Again IF my odometer is correct......WOW

I will do a GPS conformation tomorrow.

Thanks to the board

M

Not to rain on your parade, but that seems unlikely. These cars do well to see 30 mpg (usually closer to 25). You really can't use the fuel gauge to judge, you need to use a full tank of fuel, preferably several tanks to get a good average. I would also check the odometer against the GPS, they do tend to slip and they are easy to fix.

It sounds like you decided to buy that car.

I know everyone says this is not possible, but with injectors popping and spraying right, proper tire inflation, and avoiding jackrabbit starts and treating the throttle like an on and off switch, this is possible in a well maintained vehicle. I get 32.24 out of mine and divide the mileage by gallons used. The best I ever did was 38.36 on a long highway trip.

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I did, and I know you're correct. I filled up to where I could see fuel, drove 92 mi. and filled again to the same point. 2.72g of fuel.

The question is, did I really drive 92mi.?

I was guessing between 25 and30 mpg.

I will do further testing.

Thanks

M

What engine are you talking about?

It's certainly possible, depending on how you drove. All vehicles are subject to changes in fuel economy due to different types and styles of driving. An extreme example was my '86 Lincoln Town Car that once returned 12 mpg in stop and go LA traffic, but which also manged 24 mpg doing a steady 55 on a long trip along the two-laners of Virginia.

I wouldn't really be surprised to see a stock W123 hit 40 mpg if it were driven for long periods at a steady 45 mph or so with the windows up, AC off, and tires aired up to "granite". Of course, the driver might die of heat stroke, or from being rear-ended, or from being shot by the drivers stuck behind him.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.

A 1983 300D Turbodiesel with a 617.

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I'm not saying it's impossible, but it doesn't take much measurement error to change the results over a short distance. I would measure a full tank over 3-400 miles next time.

I can see getting 32 mpg if you really work at it. Sorry, but I don't see how anyone can get 38 mpg out of a 617.

This reminds me when I was in "laid-back" LA during the summer of 87 when drivers were getting shot for driving too slow.

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83 300D 328k mi (623) Light Ivory - daily driver
82 300D 166k mi (881) Thisle Green - fixer upper
82 300D 282k mi (473) Champagne - parts

I agree. Mine gets what I consider great mileage. I only compute after a minimum of 2 tankfuls and 32-33 was the best ever. I don't believe it's possible getting in the upper 30's on any stock 616 or 617.

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83 300D 328k mi (623) Light Ivory - daily driver
82 300D 166k mi (881) Thisle Green - fixer upper
82 300D 282k mi (473) Champagne - parts

My fuel economy got better after a few tankfuls of Biodiesel! I got 211.8 miles out of 5.65 gallons of fuel. That was going from Wickieup to Gold Canyon Arizona on a slight intermittent downgrade and flat land at 60MPH.

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