At a casual glance from the outside, the Mercedes-Benz W140 was a simple, streamlined design, measuring in at 201.18 inches long, 74.41 inches wide. If it didn't have the signature Mercedes-Benz hood ornament on the front, you might mistake it for an understated '90s sedan. However, the elements that made the W140 a luxury vehicle weren't in its outer appearance, but on the inside and under the hood.

The heftiest member of the W140 S-class line — the S600 SEL — featured a fearsome 5,987cc V12 engine with an output of 408 horsepower. Open it up on the highway, and you're looking at top speeds of around 155 miles per hour. It only got 15 miles to the gallon, but obviously, you don't drive a luxury sedan from the '90s if you want good gas mileage.

Speaking of cool features, the bells and whistles are where the W140 line really shined. For one thing, the interior featured full leather upholstery on the seats, paired with stylish wood trims on the dash and door cards. All of the windows were made of double-paned glass, which made them virtually soundproof, while the doors were equipped with soft-closing to prevent any unnecessary damage to the body. The windshield wipers were equipped with automatic rain-sensing technology, not to mention heater wiper fluid dispensers for that extra bit of gunk removal. Those who really wanted to protect their rides could even special-order ultrasonic parking systems that detected obstructions at the front and rear.

Even compared to today's cars, the W140 line still has some features that you couldn't find anywhere else, making it a one-of-a-kind luxury experience.