While Foster had a marketing hit on his hands with the 1937 Aero, Foster and his team kept innovating new approaches to make the scooters easier and better to ride. Foster's biggest innovations hit in 1938 and 1939. He and his team innovated the starting clutch, which made it easier to start the scooter and keep the engine running even when the scooter came to a stop. So you didn't have to restart the scooter at every stop sign and red light. He and his team also innovated the variable speed or automatic transmission, which was an incredible breakthrough - something that Vespas would not have until decades later. With the variable drive transmission, the rider doesn't need to shit gears using a hand-lever clutch and a twist grip. The variable drive transmission made riding a scooter MUCH safer and easier.

Again, nobody knows. The SRS has an internal Salsbury document indicating Salsbury was unable to ship a lot of scooters in 1938 because of delays in perfecting the automatic clutch and self-shifting transmission. But we don't have any financial information for 1938 and 1939.

Our best estimate is that Foster sold about 500 - 1000 Models 40 thru 60.

The Salsbury Restorer's Society only shows 4 1938 Models, but one of those may not be a 38. The SRS lists 3 1939 Models, but 2 of those look to be later models based on serial numbers and other info.

In a GREAT publicity stunt, Salsbury and General Tire and Rubber Company, the maker of the General Jumbo Junior tires used on all Motor Glides, sponsored two actors to drive across the country on self-shifting Motor Glides during the winter of 1938 - 1939. The actors hit many major cities, and always managed to stop and a General Tire Company outlet in each city. Lots of free press and photos.

The journey started in LA, then to SF, and then finally to NY. 4900 miles over 50 days (Oct 1938 to December 1938). The Motor Glides averaged 117.36 miles to the gallon. Fuel bill was $7.10 per scooter for the entire trip!