Diesel Cafe is an old garage-turned-coffee-shop with a very rustic vibe.  Besides in the very early hours of the morning (6 AM-7:30 AM), Diesel is almost always packed.  The usual crowd is Tufts University students or adults on a coffee break.  The vibe of this coffee shop is perfect for hanging out with friends.  Unfortunately, despite the fact that they serve Intelligentsia coffee, the coffee tends to be a little too watered down.  I find that I need to order sweeter drinks such as flavored lattes because the coffee flavor is not as bold as I like.  My favorite drink is The Accelerator which is a latte containing almond and vanilla syrups.  All in all, Diesel is a great experience, but if you feel like a great cup of coffee I would try somewhere else.