I just spent 50 minutes replacing 700 trains. At around 500 I noticed that I could speed the process up by double-clicking on the new engine, a little quicker than moving down to the buy button. Then I had a look at the engine list view where you can see 5 (I originally incorrectly said 6) trains on a screen. There is a nice little replace button on each one! So I replaced the last 50 in under 2 minutes. At that pace I could have replaced 700 in less than 15 minutes! Maybe this is common practice for some of the experienced players here, but I am putting it out there for those who don't know. Hope this saves some time, so there's more time to have fun! PS. I wanted to insert an image to demonstrate, but I have NoScript in Firefox and I think there is conflict with the Posting system on here.