I feel there were a lot of good songs from previous titles that they were left out, some examples include:
MK - 17 (In the Air Dub)
Beck - Colors
Rusko - Every Day (Netsky VIP Remix)
Cut Copy - Free your mind
Reso - Break 'Em
Justice - D.A.N.C.E.
Foo Fighters - La De Da
Pennywise - Greed
Todd Terje - Delorean Dynamite
Oliver - Ottomatic
Krakota - Mismatch
Wolfgang Gartner - Ching Ching
So my suggestion would be to add them as unlockable songs for future seasons
Oliver heldens 
Satisfy by NERO… anyone? It’s a FH2 banger.
As part of the Horizon 10-year Anniversary, we need to add these songs to the Horizon Mixtape
Reaching Out (Fred Falke Remix) by Nero - Horizon Bass Arena from FH1
The Power (ft. Dizzee Rascal) by DJ Fresh - Horizon Bass Arena from FH1
Me and You by Nero - Horizon Bass Arena from FH1
Take it Back by Toddla T (ft. Shola Ama)- Horizon XS or Pulse from FH2
Turn the Music Louder (ft. Tinie Tempah & Katy B) - Horizon Bass Arena from FH3
Satisfy by Nero - Horizon Bass Arena from FH2
Waiting (Extended Mix) by Oliver Helden & Throttle - Horizon Bass Arena from FH3
Reckless (With Your Love) - Azari & III - Horizon Bass Arena from FH1
Definitely needs those two Nero tracks adding.
Second that
Also some good songs in my opinion were: Overdrive - Geko, The Power - DJ Fresh, Make the Music Louder, and maybe a few more I do not have on top of my mind, but those already are quite tasty 
Make that 3, Satisfy by NERO. (Forza Horizon 2)
I love the music in the newly added Horizon Mixtape radio station. All 15 songs picked are classic songs from the previous Horizon games. However, out of all of the games presented on the tracklist, Forza Horizon 2 is underrepresented with only 2 songs from that game with both being unlockables. It think it needs one more song to balance it out and make it equal with the number of Forza Horizon 1 songs in the Horizon Mixtape radio station with 3 from that game.
After playing Forza Horizon 2 for a bit as a bit of my way to celebrate the 10 Year Anniversary of the franchise, Satisfy by Nero is the perfect song from that game that I and probably a lot of people that played it fondly remembers. It’s in the Horizon Bass Arena radio station, so Scott Tyler will easily remember this hit. Mixtape needs this song in Forza Horizon 5 to truely feel like every Forza Horizon game is celebrated.
Why I say pick this one? If you don’t press A on the start screen of Forza Horizon 2 for a minute or two, a cinematic of the game plays along with the song Satisfy. I hope Playground Games will be able to license a Nero song for this one. They have quite a good amount of tracks that were in Forza Horizon 1 as well, but if I had to pick one from them, it’s Satisfy.
I’m totally disappointed with Mixtape. There are so many songs I adore from Horizon 2, 3, and 4, and none of them are there. “Satisfy” is one of them. To be honest, when I read the playlist I read “Hospital Records was cheap to re-licence”. 
I was hoping for more.
I agree, it’s probably one of the very best songs because it’s so memorable !
horizon mixtape brought great additions of songs from previous horizons but there are still songs from other games that I still hope will be added to this radio in the future follow the list:
Chvrches- Clearest Blue
Chvrches- Bury it
Chvrches- Never say die
Makoto- Wading through crowds(feat.Karina Ramage)
Bop & Subwave- City lights
Silversun Pickups- Lazy Eyes
Red sun rising- Deathwish
Starset- Satelite
Joyce Manor- Make me Dumb
Saosin- Racing toward a red light
Subtact- Tunel Vision
Rusko- Somebody to Love
Dj Fresh- the power
Black Keys- Lonely Boy
Lostprophets- Bring 'em down
Nero- Me and You
Ost chase & Status ft. Liam Bailey- Blind faith
Anna Yvette- Shooting Stars
The killers- The Man(Jacques Lu cont remix)
Basanji- Runnin
SHREDDERS- Flipping Cars
Man i miss “to u” from fh3
Lykke Li i follow rivers the Magician remix
It would be cool to have back some of these song on fh5
Glantis - Runaway (U & I)
Skrillex - cinema
Nitro fun - cheat codes
Flippin Cars and Runnin from FH4 were bangers.
Sorry for bumping, I know it’s pretty late but I have a list of songs that are supposed to be in the Mixtape IMO:
Akon - sexy chick clean version
lucky twice - lucky I’m so lucky
Amy grant- baby baby
Micheal Jackson - billie jean
jack Harlow - Lovin on me clean version
doja cat - agora hills clean version
Belight - paradise
Everyday (netsky vip remix)
What’s the point of adding more music in mixtape if it always starts with the same songs at the beginning of the station? you better vote first to randomize the songs of that station.