Trying to get a complete overview here.

This should include barely-altered real sponsor names, but exclude toys like G1 Bumblebee and Cliffjumper (which have "Dunlop" tires), G1 and MP-01 Optimus Prime (who both have "Desert Dog Formula" tires), or Binaltech/Alternators Smokescreen, Dark of the Moon Roadbuster, Topspin and Leadfoot, Masterpiee Wheeljack and all of the Transformers GT figures, who have genuine sponsor decals.


The Transformers (Generation 1):
Jazz - "Martinii" (with a double "i")
Wheeljack - "Alitalla" (double "l" instead of the real "Alitalia")
Mirage - "Citanes" (instead of the real "Gitanes")
Micromaster Greasepit gas station - "Super Gasoline Z-1"
Action Master Circuit's Supersonic Racing Car - "Action Masters"

Operation: Combination:
Micromaster Circuit - "Cybertron", "Auto Bot"

Generation 2:
Rotor Force Leadfoot/Rotorbots Hot Foot - "Rotor Motor"
Rotor Force Manta Ray/Rotorbots Piranha - "Power by Autobot" (I count this because of the complete phrase)
Auto Roller Dirtbag - "Tform" (supposedly a fictional manufacturer logo?)
Go-Bot Gearhead - "Stockbird by Transformers"
Go-Bot Rumble (unreleased) - "Vinny's Pizza", Jerry's Motors"
Go-Bot "GTP Racer" (unreleased) - "GTP GoBots"

Machine Wars:
Prowl - "Prowl", "BW", "Boyc", "Pole", "Andar"
Mirage - "Mirage", "Mobile Pistons", "C.S. Cams", "lamb shocks"
Hoist - "Wilk and Son Towing"

The Transformers Collection/Commemorative Series/Encore (reissues):
Jazz/Meister - "Meister" and "Agent Meister"

Alternators:
Side Swipe, Hound, Dead End, Tracks, Meister, Swindle, Battle Ravage, Windcharger, Shockblast, Decepticharge, Swerve, Prowl, Skids, Sunstreaker, Broadblast, Rollbar, Mirage, Optimus Prime, Camshaft, Rodimus, Nemesis Prime, Rumble, Ravage (Jaguar), Arcee, Argent Meister - "Cybertronian Radial" tires
Decepticharge - "Dinotron Racing Fuel", "Energon Power", "Cybertronian Radials" (with a plural-"s"), "Thrust Power", "Destron Oil", "Hyperlinq Racing", "Dualor Exhaust", "Sporal Plugs" (?)

RobotMasters:
"Rijie" (Mirage) - "RobotMasters"

Classics:
Deluxe Mirage - "Witwicky Sparkplugs", "Lithonian Drivetrain", "Plasma Injection Energy", "F.P. Racing"

Transformers (2007 movie line):
Deluxe Longarm - "Orson's Towing" (single release), "Mike's Towing" (Screen Battles version)
Deluxe Salvage - "Sparkplug & Son Salvage"

Timelines:
BotCon 2008 exclusive "Shattered Glass" Jazz - "Massacre" and "Massacre Racing"
BotCon 2013 exclusive "Machine Wars" Mirage - "Illusions Motorsports", "Mobile Pistons", "lamb shocks"
BotCon 2013 exclusive "Machine Wars" Hoist - "W&S Towing"
Transformers Collectors' Club Subscription Service exclusive Carzap - "Transformers", "Heroic Autobots", Generation 2 Autobot insignia (I usually wouldn't count any of those, except they appear on the same figure as the following one), "Blocktown Racing"

Revenge of the Fallen:
Scout Reverb - "Calany Racing" (misspelling of "Colony Racing")
Scout Wideload - "Energon Express"

Power Core Combiners:
Leadfoot - "Blackrock"

Speed Stars:
Stealth Force Leadfoot - "Blackrock Racing"

Dark of the Moon:
Human Alliance Icepick - "FreCon"
Walmart exclusive Deluxe Bumblebee - "Fly Omega Supreme" (using the Greek letter "Omega"), "S.T.A.R.S.", "Ancient Robot"/"Prehistory Autobot" insignia (from "Five Faces of Darkness"), Mini-Con insignia (from Armada), Sumdac Systems logo (from Animated), Playschool Go-Bots insignia, "Black Rock", Dinobots insignia (from Beast Machines), "Maccadam's"
Walmart exclusive Deluxe Sideswipe - "Lithonian Drivetrain", "Axalon Rattraps - Safe, Humane, Yeah, right!", "Sun bro", "Maccadam's", TransTech Autobot insignia

Masterpiece:
Smokescreen - "Huck", "Disturbance", "Devcon Oil", "Smoke Tactics", "SlotFever"
Exhaust - "GoodFlavor", "Sidestream"

Age of Extinction:
Platinum Edition Breakout Battle Rollbar - ""Dinotron Racing Fuel", "Cybertronian Radial"

Movie Advanced Series:
Dispensor - "Mood Whiplash"

Adventure:
Junkion - "Eco Clean"

Combiner Wars/Unite Warriors:
Mirage - "Circuit Racing"

Power of the Primes:
Jazz - "Energon"

Studio Series:
Roadbuster and Topspin - "Ultra Wreckers" tires

War for Cybertron: Siege:
Amazon exclusive Fan Vote Battle 3-pack Mirage - "Visages", Zarak Consortium logo (from the IDW comics), CBC (Cybertronian Broadcasting Company), "Onyx" (from the IDW comics), unknown insignia/head(?), "EMP"

War for Cybertron: Earthrise:
Deluxe Wheeljack - "'Wheeljack' Invenzione", "Modulator", "サイバトロン" ("Cybertron" in katakana), "Iacon", "Lucky!", "W Motors", "Autobot works", "Rally X", "Ricochet", "Cybertron Con" (that one's not really fictional, I'm just including it for the sake of completeness), "Velocitron Racing 1984", "Praxus", "Protihex", "Swerve", "Aerobolt" plus a few more I can't make out yet

 

Combiner Wars Breakdown - “15Racing” tampo on the windshield. Unless 15 Racing is a real thing.

CW G2 Breakdown has “94 Racing” on the windshield.

 

They're racing cars. That's it.

G1 Getaway simply had "Racing" written on his windshield.

Combiner Wars Breakdown's number refers to the year the toy was released in (2015). Combiner Wars G2 Breakdown's number refers to the year the original G2 Breakdown toy was released in as the first-ever BotCon exclusive (1994).

Dark of the Moon Walmart exclusive Deluxe Bumblebee also has the number "84" plastered all over his alternate mode (which refers to the year 1984, of course). I interpreted that as his racing number rather than a sponsor decal.

 

Off the top of my head, RotF Reverb - "Colony Racing"

 

Actually it's a misspelled "Calany Racing", though the intent sure was for it to be "Colony".

 

IIRC, the G2 Color Changers had some stickers that might be sponsors, but might also be driver names or just random names slapped on them.

Deluge has two "M. Edminson" stickers and Jetstorm has 'Phil something' on a sticker, as well.

MIKE
engledogg

 

Should Masterpiece Exhaust count?

 

He's already on the list!

 

RotF Wideload has Energon Express.

 

AoE Rollbar has Dinotron Racing Fuel.

 

Although it is definitely real, I just wanna put this out there.

Also, random energon brand promptly named...well...you know.

 

TFCC Carzap has Blocktown Racing.

 

I think you were adding him at the same time I posted. I'd swear he wasn't there when I first went down the list.

 

I can easily avoid the controversial one by stating that I only count A) graphics and B) texts in human fonts, so no made-up alien writing.  

 

But Energon Brand Energon...

 

Added G2 Dirtbag, ROTF Wideload, POTP Jazz, Timelines SG Jazz and Carzap.

 

SS Roadbuster has “Ultra Wreckers” tires, ‘07 Movie Salvage has “Sparkplug & Son Salvage” logos, and ER Wheeljack has a fair few:

 

G2 Deluge has a sticker that says "Bradley" and another that says "M. Edminson". One of his 5's has the word "Sport" over it, but I'm not sure that counts.

 

I think those are supposed to be driver names rather than sponsor decals.

 

All right. Added G1 Micromaster Greasepit, G2 Manta Ray/Piranha plus Go-Bots Gearhead and "GTP Racer", Machine Wars Hoist, Timelines BotCon "Machine Wars" Hoist, 2007 Movie Longarm and Salvage, Movie Advanced Dispensor, Studio Series Roadbuster and Earthrise Wheeljack, among others.