Bitcoin (BTC) - Bugatti 

Bitcoin is the OG of crypto with a household name. Just like Bitcoin, Bugatti is one of the OGs in the car world whilst having a well-known reputation among car enthusiasts and non-enthusiasts. They both start with the letter "B". Both are highly sought after. Maybe one day 1 BTC can buy a Bugatti!

Ethereum (ETH) - Porsche

Okay so I had to pick another one of the older car makers. I didn't want to use Volkswagen so I opted for Porsche instead. A myriad of car manufacturers are owned by the same company as Porsche. I thought it was neat to use that to make a comparison to Ethereum since other alt coins run on ETH.