Road & Track, August 1970

MY MERCEDES 250SL is the seventh 2-seat roadster for me and probably won't be my last. Much as l like GT cars with +2 rear seating and/or fastback rooflines, I just can't give up that ragtop for sunny days or warm nights--not yet anyway, even though noisy traffic and smog make top-down driving less and less enjoyable.

I worked my way up the capitalist--materialist car ladder through three MGs, an Austin-Healey, a Jaguar and a Corvette to arrive at the SL, my most sedate roadster yet. The SL isn't a car for kicks--unless one gets kicks out of a precision bit of machinery, which I do--but I road test so many fast, exciting cars that I don't really need that kind of excitement in my everyday transportation car. Furthermore, being single, I can't justify having two cars so my one car has to be all things: an about-town car for errands and a comfortable, quiet one for freeway runs (which are frequent, as I live 50 miles from Los Angeles) and the occasional long trip, during both of which I expect to be able to listen to an FM radio or tape deck without turning it up to a roar. Hence the SL.  

Mine is a 1968 250SL of mid-1967 manufacture; it's a coupe-roadster, which means it has the removable hardtop as well as the soft one, and it's my first car with automatic transmissions and power steering. I've always had mixed feelings about the M-B automatic; it's probably the world's most efficient fully automatic box but, as we've pointed out in road tests (this is the "old" box, which normally starts in 2nd gear and has a very rough 2-3 shift) , its idiosyncrasies can be bothersome. A 2.5-liter engine driving a 3000-lb car is a torqueless wonder in the east place and if your gearbox. is starting off in 2nd instead of 1st and overcoming the drag of a band in the gearbox that reduces creep at idle, mashing the throttle produces results remarkably like flushing a toilet. And I had wondered after road testing various Mercedes how long the driveling would hold up under those jerky shifts.

Well, after 35,000 miles I like the transmission better than I ever thought I would. With age that creep-control band must lose some of its effectiveness because the car moves off more smartly now, and wear of various internals has apparently smoothed out the shifts. The U-joints and other parts in the drivetrain are still tight in spite of my hard driving, so most misgivings I originally had were unfounded. And the way it shifts when I'm driving full-bore is delightful.  

The only defect in the car when new didn't show up until about 4000 miles. When the fabric top is folded, its rear edge is brought up to the center bow, into which it locks, and then the whole thing is lowered and stuffed into the well. The brackets that effect this locking of rear into center bow were incorrectly made, not locking securely, thus when the top was lifted out of the well the rear edge would fall and the fabric below the rear window would chafe. I reported the chafing to the service department of the M-B factory store in Hollywood, where I bought the car, and the service manager immediately recognized the trouble and ordered the brackets. When these arrived about a month later they were installed along with a new top, which has worked perfectly since. The top is of what appears to be old-fashioned canvas so I don't thank it will be as durable as the vinyl material of my Corvette, but it fits as perfectly as any convertible top I've ever seen and is in good condition 20 months later.

Oh, there was one other defect: a lone rattle. In the dash somewhere I picked around looking for it for a long time, one day the radio speaker developed a vibration on bass notes and when I took it out to fix it (simply bending a wire soldered to it solved the problem) I discovered the radio's front end had been laid on top of its locating bracket rather than clipped around it, so the radio was bouncing up and down. After undoing the radio's face plate and jockeying it around for an afternoon into place, the rattle was solved

The just "replacement" item lasted is the windshield wiper blades. These have broken up twice, not being able to take our ozone-laden atmosphere, and replacing them is a delicate little operation that involves extricating their metal stiffening straps before the rubber.

I have not followed the factory-recommended routine maintenance schedule to the letter, but I did stay pretty close to it in the warranty period (24,000 miles). Rather than going to an M-B dealer, the nearest of which is ten miles away, I use an independent Mercedes mechanic who's only six blocks from the office, Bob Wombles. Bob is one of those rarer and rarer mechanics who actually understands what he's doing and can think a problem through rather than just changing parts, so I feel the car is in good hands.

Believe me, maintaining a Mercedes isn't cheap even if one leaves out some of the more persnickety items on the service ritual. The routines for 3000, 9000, 15,000 miles, etc, are pretty light and I have either had only the chassis lubrication or the oil changed as well if the car was being driven in a lot of short-run use. But the 6000-mile service (12,000, 18,000, etc) includes a minor tuneup--clean spark plugs, adjust taming, reset idle--and can easily get over $30. And the 12,000--wow!

At 12,400 miles I had Bob do what he considered essential, eliminating the prescribed transmission and differential oil changes and the brake disassembly; there were no problems with wheel alignment or with the transmission.

Spark plug fouling is the ailment of a high-speed engine that's run at low speeds and the SL engine is no exception. By 5000 miles the plugs were dirty enough that the engine would begin to cut out at 5500 rpm; as the automatic box shifts at 6000 on wide-open throttle or can be held manually to 6500 rpm, this meant less than maximum performance. I had the plugs cleaned at 6000--the original Beru D250/14/3S debut before long they were pretty badly fluffed up again. So at the 12,000 I let Bob install what he felt was the solution: NGK B7E plugs. Conclusion on them: they're not entirely immune to fouling, but five miles at 70 mph will clean them up so that the engine can be redlined nicely. The bill for the 12,000-mlle service was $60.59.

A month after that service the windshield washer quit squirting and I took the car to the Santa Ana M-B dealer, Jim Siemons, to get it fixed. The treatment I got there was startling: without any rigmarole the service writeup man whisked the car off to a stall and in a half-hour I had the car back with an operative washer. I was so stunned I forget to find out what they did!  

Somewhere along in here I had taken the car back to Hollywood to get the headlight flasher wired up. That is the device that allows the driver to flash the bright beams, day or night, by simply pulling the directional-wiper-washer master stalk on the steering column toward him against a spring load. In Europe this is the recognized signal for "Get over, I want by (please)" and m California it is gaining recognition. So I felt it was well worth the $12 it cost to get the thing connected. Mercedes delivers cars to the U.S. with it disconnected because it's illegal in some states.

At the 15,000-mile service Bob told me I needed a new muffler but as it wasn't noticeably noisy I postponed that. He also noted a dribble of hydraulic fuel from the master cylinders so I headed for Jim Siemons' again. This time I left the car for a day and the cylinder was replaced satisfactorily on warranty. No leaks since.

The Firestone Phoenix 185-14 tires were generous for a 3000-lb car when the SL was introduced in 1963, but these days they seem mighty small. When they were worn out at 17,500 miles I decided to fit something larger. I settled on a tire that had impressed me on the 300SEL 6.3, the Dunlop SP CB57 in size FR70-14. As these are over an inch wider than the 185s, I accepted some scrub with the sheet metal when the front wheels are cramped over and hit a bump, but the improvement in cornering power is well worth the occasional scrape. These are about half worn now--meaning they'll last twice as long as the originals--and they too are prone to squeal at low speeds. Perhaps I should blame that on the suspension. Anyway, to get rid of the squeal I've settled at 30 psi front, 35 rear instead of the factory recommended 26/31.  

Between 18,000 and 24,000 miles there are no entries in my log book except a comment that oil consumption had decreased. It had been about 1500 mi/qt after the break-in period, but now it was (and remains) about 1700. Can't complain about that.  

At 24,100 miles I braced myself for the worst--the full service ritual including all full changes and a new exhaust system. My fears were confirmed $70.38 for the routine service, $98.80 for the exhaust system job including new chrome tips. Strangely enough, the NGK plugs did not need replacing. Nor at this point was there anything else that needed repairs: the brakes appeared to have another 20,000 in them and the shocks were still firm.

After all this experience with the car I had really become disenchanted with its handling characteristics. The SL was outstanding in 1963 but is behind the times now with its low-pivot swing axles at the rear and lack of anti-dive in the front suspension. In addition, my car seemed to have more than its share of positive camber at the rear. So at this point I had Bob rotate the mounting pads for the rear coil springs, which reduced the camber by about a half-degree; labor charge for this was $30. There's still some positive camber, though, and my next move is to see if the rubber shims in my particular car (for the coil springs and the center compensator spring) are the thinnest possible; If not, the thinnest ones will be installed. As it stands the car is just a little too prone to final oversteps for my tastes.

At about 27,000 miles the SL failed me for the first time. I was motoring at 70 mph on the freeway when the gearbox started hunting between and and 4th. So I got off at the next exit, pulled into a service station and found transmission fluid all over the bottom of the car. The high-temperature hose from the transmission to the oil cooler up front had ruptured. It was a Saturday afternoon and I was sure I was stranded, but a call to Bob found him there and he had a hose. A friend picked it up and delivered it to me, I changed it myself, replacing two quarts of lost oil. Bob tells me that these hoses don't ever last long and that he replaces them with some Weatherhead high-pressure tubing, but in the interests of getting underway quickly I bought the regular item. The low-temperature (return) hose is still OK.

A little over a month later, SL let me down again will. I'd left it out overnight in a driving rain and the next morning it wouldn't start. By this time the NGKs had 18,000 miles on them so I just bought a new set and screwed them in. It didn't work, and the plugs I took out appeared to have a few thousand still left in them! Sanding the points, which had a little corrosion formed on them, is what got the car going again. The new plugs, by the way, are B7ES, supposedly an improvement on the B7E with a wader heat range, but they perform exactly as the B7Es did in the SL.

The only other trouble I've had is a decline in fuel economy since about 24,000 miles. I've never been very happy with the way the car uses fuel--it was doing 15.5 mpg at the beginning--but it had dropped below 15 by this time. Bob twiddled the idle-mixture control several times as I returned with grim reports of slim improvement and really got the idle so lean the engine started stalling during the warmup period. Internal adjustments of the injection must be done at a regional service center, so for now I've returned the idle mixture to a setting that keeps it idling correctly all the time and am getting about 14.5 mpg. At 36,000 miles I'll have the unit adjusted, but I'm not eager to have a premature tuneup done just to gain a mile per gallon. Any other comments on the fuel injection are favorable. It gives good idling and general running and never deteriorates noticeably in these respects between tuneups.

If I had to pick the one thing I like least about the car it would he the noisy tappets. At low speeds they're really obtrusive, and one of them always seems to be looser than the rest. As engine speed builds up they blend into the general sound. The engine has become notably smoother, quieter and more willing with the accumulation of miles and the feature I thought would be the greatest annoyance--gearing that turns the engine 4000 rpm at 70 mph--no longer bothers me much. Coming from a car that did 3000 rpm at the same road speed, I had to get used to this, but the Mercedes engine is not very noisy at high speed and only the tach remands me how fast it's winding. The lack of low-speed torque could be a bother too, but I simply take advantage of the gears available, either by kicking down the throttle or manipulating the precise little shift lever, and the car seems happy to be driven hard.

I'm not very happy with the driving position. I have short legs and a relatively long upper body, so to get far enough back from the wheel for an arms-out stance I have to put the seat back far enough that I can't rest my foot on the floor dimmer switch. Thus I have to move my whole foot to dim the lights; if I were designing the car I'd mount the switch lower on the toeboard--or better yet combine it with the steering-column stalk as on the smaller Merc sedans.

The most satisfying thing about the car is its great precision of operation and quality of manufacture. It's the sort of thing you're not sure will last when you drive a road test car for 1000 miles or so, but I can say with conviction that in this Mercedes it has lasted. At 35,000 miles the car is still rattlefree (remarkable for an open body), devoid of water or wind leaks and lacking any tattiness of upholstery or trim save one pulled seam on the back of the passenger's seat. The engine and transmission, as I mentioned, are better than new--so the car is more impressive than when new.

Speaking of being more impressive than new, right after the engine was freshly tuned at 30,000 miles, a friend and I checked the car's acceleration, I was especially curious because we never got to test a 250SL, our test car having been crashed into before we got it back to the office. My car turned the quarter-mile in 17.5 sec, doing 79.5 mph at the trap, and did 0-60 mph in 10.1 sec. That's within a hair of what our test 280SL. did, so the break-in miles must help.

According to a report recently issued by the Federal Highway Administration, the average American motorist spends 11.9 cents per mile to run his car. So I guess the Merc hasn't done badly at all--lf one can operate a car like this for no more than it costs to run a domestic sedan it's a bargain. The delivered price quoted in the table is full retail, a haggling customer usually gets a few hundred off. Similarly the Kelley Blue Book resale value is inflated, but we use these for consistency--so the two should cancel out. My relatively high annual mileage helps keep the per-mile cost down; Dean Batchelor's Alfa GTV (a 1967 1600 model) cost him 11.5 ¢/ mi even though its fuel economy is much better and he didn't have to replace tires, but he drove only 24,000 mi.

Will I drive it another 35,000? I doubt it, but it won't be because I don't like the car. My present plan is to get something different every couple years so that I can get a maximum amount of experience with different cars and report it in R&T. But the SL is going to be difficult to replace.