Good mileage!

[Richard Wooldridge]

Hi there,
I made a 305 mile trip today from north of Vancouver, WA to Medford, OR. and decided to put the cruise control on at 67 mph and see what the car would do for mileage. It's a 1982 380SL that has a 560SL engine installed. Amazingly enough (to me, at least), it produced 21.5 mpg on the drive! I had previously driven the same trip with the cruise off, and travelling somewhat faster, more like 75 -80, and gotten 19.8 mpg, but I was surprised that lowering my speed by 10 mph would give me such good results. I guess I'll have to try not to lead-foot it so much.
My 1979 450SL only gives around 18 mpg at it's best, and I attribute the decreased economy to the poorer rear end ratio- the poor engine is turning over 3100 revs at 65, where the 380SL is only doing 2400 rpm at the same speed.

[Jim B.]

As the purchase price for new 560 engined cars was roughly was from $50-$80k, if you could afford to buy one, the cost of fueling it was thought to be of no concern to their first owners.

That said, I never bettered 18.5 mpg on my coupe, so I'd say you are doing very well. The techron additive in the Chevron Supreme really does clean the injectors as you dirve, so that's all I ever put in it, and have not experienced driveability problems with the car.

[kknudson]

Actually I just got back from a 600+ mile round trip.

Loved it in the SL, cruised part way at 85-87, with an over an hour on cruise.
Ran a little harder for another part just under 90.

The trip out was in the rain, not enough to even put the top up, and half the tank was year old gas. 19.33 on the way out.

The trip back was perfect weather for the top down. Just under 19.

Not quite as good as I hoped, but hey.

(Pushed up 20s MPG in my brothers 92 Vette on a long cruise years ago).

[Pete Geither]

Average from 22 to 24 on most trips with the SL.

[jjrodger]

Me too: 22 to 24mpg almost every time.

On a long highway trip I can get 27.

Most recently I ran 550miles from my home in Northumberland to Normandy in France at a steady 90 to 120mph with 60miles (Channel Tunnel terminus in Calais to Les Tourelles restaurant in Le Crotoy) at 120 to 155mph (we were late for dinner, covered the 60miles at an average of 120): 25mpg on the nail. 375miles off 3/4 tank. Car was fully loaded, too.

The SL500 is better for fuel than my C240 ever was.

[Dee8go]

Originally Posted by jjrodger

Me too: 22 to 24mpg almost every time.

On a long highway trip I can get 27.

Most recently I ran 550miles from my home in Northumberland to Normandy in France at a steady 90 to 120mph with 60miles (Channel Tunnel terminus in Calais to Les Tourelles restaurant in Le Crotoy) at 120 to 155mph (we were late for dinner, covered the 60miles at an average of 120): 25mpg on the nail. 375miles off 3/4 tank. Car was fully loaded, too.

The SL500 is better for fuel than my C240 ever was.

Why do you suppose that is, JJ? It seems contrary to logic. I would say maybe the SL is lighter, so the engine has to pull less, but I doubt it's lighter than the C240, don't you?

[jjrodger]

I expect the SL is slightly heavier than the C. The C240 was actually really disappointing: for all it was very smooth, it was not very fast. I think I had to work the C much harder than I do the SL to get similar sort of speeds out of it. So while most of the time I must use about 50% or less of the SL's available power, in the C240 I reckon it was 90% or more. The C240 had lower gearing, too, so 70mph was 3,000rpm not 2,000rpm.

The outcome certainly surprised me when I bought the SL.

[page62]

The C240 is really the dog of the C-class engines. Even the 230K engine has more pep. But it's the C320 that's got the get-up-and-go (at least among the non-AMG variants).

And the C320 will get 26-27 mpg at 80 mph cruise. Not bad considering it's running at a bit over 3000 rpm.

[Carlos Serrano]

JJ, you are a brave man I don't see myself driving at 155 mph in my SL 500 that is the top speed of USA models with electronic governors, 145 MPH is the fastest I've driven mine and that was in a rather short period of time, the other guy in the Dodge Viper backed off first. Tire blowout, deer on the road, loose lug bolt and wildlife on the road in general came to mind seconds after the deed was done and now it comes to mind before I even start, maybe I'm getting old, I take my hat off to you Sir.

Here in California getting caught for speeding
at over 100 mph gets you two points, safety classes
& a jump in insurance rates & perhaps more problems. I found this out in traffic school last month.

Ive made a deal to never go over 100 again. Once in my sl made it to 105 and the car seemed to light headed. My car runs well at between 85 & 95 but i can't go speeding around for a year or so.

My friend told me he has his new vette to 130 last week. His wife didn't realize he was going that fast.

best to all and stay safe

steve

84' 280sl 5 speed 187k
'70 datsun roadster 137k ( daily driver)

[jjrodger]

The law's against me in Europe, too. They've really cracked down on speeding in France, which is a shame because their autoroutes are beautifully built and engineered and very lightly trafficked. If ever there was a country in which it is possible to cover ground quickly, in safety and without inconveniencing others, it's France.

As to the SL, I find it really comes into its own at very high speed. The suspension starts to work properly and the ride evens out. I find it very stable at high speed. It is in its element at 90 to 120mph. For the record, I've seen an indicated 160 three or four times and I've forayed up to 150+ on times too numerous to count. The car was built for this kind of work and mine gets aircraft-like maintenance. And I figure that in the event of a catastrophic failure, I am as dead at 100 as I am at 150.

There's a debate on speeding and everyone takes a different view. Let's not go there.

[Bondavi]

Originally Posted by jjrodger

There's a debate on speeding and everyone takes a different view. Let's not go there.

Amen to that.

My 107 500SL seems to settle into a melodious tone around 120MPH, as if it is happy. Ride, engine noise and the car behaviour is a lot more mellow than it would be at 70MPH. Too bad California keeps me constrained as well.

Great cars!

[nobby]

I could probably get my 280sl up to 145-150 mph......On a really fast tow truck.....

Mine likes 85 mph. At least thats when the vibrations stop.....

[cbdo]

Haven't had, the 560SL over about 105, and that only momentarily; rock solid at that pace, and obviously had more left (as expected).

Drove southern German autobahns on a trip in May; wish I'd had my Benz instead of a rented Opel Signum! The limitless speed on rural sections was fun, but with a *very* full car and wife and daughter aboard I didn't push it. What was even nicer was that wonderful German thing about driving on the right, passing on the left--just a fond memory here in Michigan (sigh)

[BenzToy]

Originally Posted by cbdo

Haven't had, the 560SL over about 105, and that only momentarily; rock solid at that pace, and obviously had more left (as expected).

Drove southern German autobahns on a trip in May; wish I'd had my Benz instead of a rented Opel Signum! The limitless speed on rural sections was fun, but with a *very* full car and wife and daughter aboard I didn't push it. What was even nicer was that wonderful German thing about driving on the right, passing on the left--just a fond memory here in Michigan (sigh)

I don't think they teach that anymore. It is a shame. Bought car. About 12-15mpg Just changed the plugs on my new (to me) 1980 450SL. What a difference it made. Unfortunately, I have the 85mph speedometer in it so I don't know for sure where I backed off but it was close to 100mph. No deer. Thank goodness. Will check mileage with foot out of firewall. Bet it will be better.