BMW 300 (Isetta)

BMW 300 (Isetta)

Manufacturer	BMW
Also called	BMW Isetta
Production	1955-62 161,360 produced
Predecessor	BMW 250
Successor	BMW 600
Layout	RR layout
Engine(s)	298cc cc single cylinder 4-stroke (53 mph (85 km/h) top speed)
Transmission(s)	4 speed manual

The BMW 300 was a small car produced by BMW, featuring a characteristic front-opening door and three wheels. It was a modified version of the BMW 250 (Isetta).

The Isetta's front-opening door

Overview

In October 1956 the Isetta Moto Coupe DeLuxe (sliding-window Isetta) was introduced. The bubble windows were replaced by longer, sliding side windows. The engineers had enlarged the single cylinder to a 72 mm (2.8 in) bore and 73 mm (2.9 in) stroke, which gave a displacement of exactly 298 cc, and at the same time they raised the compression ratio from 6.8 to 7.0:1. In this way the engine now generated 13 hp (10 kW) at 5200 rpm, and the torque rose to 18.4 N·m (13.6 ft·lbf) at 4600 rpm. The maximum speed remained at 85 km/h (53 mph), yet there was a marked increase in flexibility, chiefly noticeable on gradients.

In addition to the quest for better performance, there was another reason for the change: it was then still possible to drive the 250 cc Isetta with the old Class IV driving licence. Quite a number of Isettas were lovingly maintained by their owners for years and even decades, precisely because they possessed no other licence. On the other hand, from 1956 onwards, first-time drivers had to pass the test for Class III if they wanted to drive a car. True, the Class IV licence continued to be issued, but it was only valid for small motorcycles.

A second, similar reason for fitting the larger engine was the prevailing tax regime. The 250 cc engine did not take full advantage of the tax class, which then went up to 300 cc.