The first generation, introduced in 1990, had only one sliding side door for the rear passengers. It featured a unique mid-engined platform, where the in-line 4-cylinder gasoline-powered engine was installed almost flat (at a 75-degree angle), beneath the front seats. Installing the engine in this configuration allowed easy access to the spark plugs, which were located underneath a panel on the upper right-side of the vehicle, after tilting the front seat backward. All engine-driven accessories, such as the alternator, power steering pump, air conditioning compressor, and radiator fan, are accessible from the front hood, driven off the front of the engine by an accessory driveshaft, and is known as the Supplemental Accessory Drive System, or "SADS." This allows for even front/rear weight distribution, which benefits ride quality and handling. However, it also prevents the installation of a larger engine, while the cost could not be relayed by sharing the platform with other vehicles.