Learn Spanish (Latin America): Ahorraremos mucho dinero en el trayecto largo, ¿no? - We will save a lot of money on the long journey, right?

Both mean 'we will save', but at the B1 level you are seeing more of the simple future tense. It is formed by taking the full infinitive ahorrar and adding the ending -emos for the 'we' form. While vamos a ahorrar is extremely common in casual speech, ahorraremos is great for future predictions or making factual statements about upcoming events.

What is the difference between trayecto and viaje?

While viaje means 'trip' in a broad sense (including your destination and activities), trayecto specifically refers to the physical journey, route, or travel time between two points. Using trayecto emphasizes the actual transit itself, which is where the money is being saved (perhaps on gas, tolls, or tickets).

Can I use ¿verdad? instead of ¿no? at the end of the sentence?

Yes, both ¿verdad? and ¿cierto? work perfectly here to ask 'right?'. However, ¿no? is very commonly used as a quick tag question at the end of a positive statement to check for agreement. Just keep in mind that if the main statement is negative (like 'We will not save money'), you should generally use ¿verdad? instead of ¿no?.