Buried way down in the bottom of the article we have:
"The manual for the Smart Fortwo repeats the warning issued
for other vehicles sold by Mercedes-Benz: "To maintain the engine's
durability and performance, premium unleaded gasoline must be used."
My Volvo V90 called for Premium. With all it's electronics, it still did not like anything but Premium.
My Jeep Wrangler 4.0 is supposed to run on 87. And that's what I usually buy. But guess what? When I started buying 93 or 94 for the Crossfire I accidentally put some in the Wrangler - and it had more pick-up, and got noticeable better mileage... I haven't done it since, but it was interesting.
I do not plan to put anything other than Premium in the Crossfire...
Owners Manual
Starting and Operating
Page 149
FUEL REQUIREMENTS
Your engine is designed to meet all emissions
regulations and provide satisfactory
fuel economy and optimum performance
when using high quality unleaded gasoline
having an octane rating of 91 or
higher. DaimlerChrysler Corporation requires
the use of 91 octane or higher premium fuel to
minimize the potential for engine damage.
Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and should be reported to
your authorized dealer immediately. Engine damage
resulting from operating with a heavy spark knock may
not be covered by the new vehicle warranty.
Poor quality gasoline can cause problems such as hard
starting, stalling and stumble. If you experience these
problems, try another brand of gasoline before considering
service for the vehicle.
Over 60 automobile manufacturers around the world
have issued and endorsed consistent gasoline specifications
(the World Wide Fuel Charter, WWFC) to defineengine performance, and durability for your vehicle.
DaimlerChrysler Corporation recommends the use of
gasolines that meet the WWFC specifications if they are
available.
Reformulated Gasoline
Many areas of the country require the use of cleaner
burning fuel, referred to as “Reformulated Gasoline”.
Reformulated gasolines contain oxygenates and are specially
blended to reduce vehicle emissions and improve
air quality.
DaimlerChrysler Corporation supports the use of reformulated
gasolines. Properly blended reformulated gasolines
will provide excellent performance and durability
of engine and fuel system components.
Gasoline/Oxygenate Blends
Some fuel suppliers blend unleaded gasoline with materials
called oxygenates such as 10% ethanol, MTBE and
ETBE. Oxygenates are required in some areas of the
country during the winter months to reduce carbon
monoxide emissions. Fuels blended with these oxygenates
may be used in your vehicle.
CAUTION!
DO NOT use gasolines containing Methanol. Use of
these blends may result in starting and drivability
problems and may damage critical fuel system components.
Problems that result from using methanol/gasoline blends
are not the responsibility of DaimlerChrysler
Corporation and may not be covered by the Limited
Warranty. While MTBE is an oxygenate made from
Methanol, it does not have the negative effects of Methanol.
MMT in Gasoline
MMT is a manganese containing metallic additive that is
blended into some gasolines to increase the octane number.
Gasolines blended with MMT offer no performance
advantage beyond gasolines of the same octane number
without MMT. Gasolines blended with MMT have shown
to reduce spark plug life and reduce emission system
performance in some vehicles. DaimlerChrysler Corporation
recommends using gasolines without MMT. Since
the MMT content of gasoline may not be indicated on the
pump, you should ask your gasoline retailer whether or
not his/her gasoline contains MMT.
MMT is prohibited in both Federal and California reformulated
gasolines.
In Canada, MMT can be used at levels higher than those
allowed in the United States. For this reason, it is even
more important to look for gasolines without MMT in
Canada.
Materials Added to Fuel
All gasoline sold in the United States is required to
contain effective detergent additives. Use of additional
detergents or other additives is not needed under normal
conditions and would result in unnecessary cost. Therefore,
you should not have to add anything to the fuel.
Sulfur in Gasoline
If you live in the Northeast United States, your vehicle
may have been designed to meet California low emission
standards with cleaner burning California reformulated
gasoline with low sulfur. If such fuels are not available in
states adopting California emission standards, your vehicle
will operate satisfactorily on fuels meeting Federal
specifications, but emission control system performance
may be adversely affected.
Gasoline sold outside of California is permitted to have
higher sulfur levels, which may affect the performance of
the vehicle’s catalytic converter. This may cause the
CHECK ENGINE light to illuminate. DaimlerChrysler
Corporation recommends that you try a different brand
of unleaded gasoline having lower sulfur to determine if
the problem is fuel-related prior to returning your vehicle
to an authorized dealer for service.