PROFLEX Connect vs Knuckle Log
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
PROFLEX Connect
This app allows you to monitor your vehicle's fuel system performance in real-time. It displays device settings and helps locate nearby E85 fuel stations for convenient ethanol blending.
- Real-time device setting display
- E85 station locator
- Fuel ratio monitoring
- Performance flex fuel system integration
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PROFLEX Commander is a bolt on performance flex fuel system allowing your vehicle to make big power with ethanol right out of the box. No tuning needed. The PROFLEX Commander and FLEXLINK family of devices allow you to run any blend of gas and E85 at anytime, while always delivering the exact fuel ratio to your vehicle. The PROFLEX Connect app allows you to view your device settings in real-time, and even help you find a nearby e85 station.
Knuckle Log
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The record of the work you did yourself. Every log app tracks oil changes. Knucklelog vets the proof. Snap the receipt and the record fills itself in — vendor, date, total, part numbers — then gets checked against your odometer history and locked into a ledger a stranger can trust. LOG IT IN SIX TAPS Pick the vehicle, tap the job, snap the receipt. Date and mileage fill themselves in. No receipt? Log it anyway — your word, on the record. THE LEDGER KEEPS SCORE Every vehicle carries its full service history: verified jobs, flagged gaps, documented spend, odometer timeline. Nothing slips, nothing fades. DUE MEANS DUE Set intervals once. Knucklelog watches the calendar and the odometer, and reminds you before the job is late — and nags politely once it is. THE BUYER REPORT When it's time to sell, export the whole verified history as a clean, shareable report. DIY history usually hurts resale — a vetted record flips that. YOURS, OFFLINE, PORTABLE Works in the garage with no signal — records queue and sync when you're back. Export a complete JSON snapshot anytime. Delete your account and all its data in-app, no email required. PLANS Free: 1 vehicle, on-device receipt OCR, the full ledger, torque specs, and fuel log. Basic ($24.99/yr): 2 vehicles, AI receipt scans (10/mo), buyer reports included, cloud sync. Premium ($49.99/yr): 10 vehicles, AI scans (25/mo) — room for the project cars. Or unlock a one-time Buyer Report for a single vehicle ($35.99). Subscriptions renew yearly until canceled in Settings. Terms: https://knucklelog.com/terms · Privacy: https://knucklelog.com/privacy
Screenshots
Verdict
The clearest difference is in-app purchases: PROFLEX Connect at none against Knuckle Log's 3. PROFLEX Connect also leads on iOS requirement (12.4 vs 17.0). On price, update cadence, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Knuckle Log sells 3 in-app purchases, starting at $24.99 per year. PROFLEX Connect asks for nothing beyond the download.
Both ship on a similar rhythm, roughly weekly. The most recent releases landed on October 16, 2026 and September 18, 2026 respectively.
| Parameter | PROFLEX Connect | Knuckle Log |
|---|---|---|
| Price | Free | Free |
| Rating | 2.8 (54 ratings) — better | — |
| Positive reviews | 37.9% of reviews | — |
| Number of ratings | 54 — better | — |
| Update frequency | Weekly | Weekly |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Monetization | Free | — |
| Devices | iPhone, iPod — better | iPhone |
| Requires iOS | 12.4 — better | 17.0 |
| Further details — not scored | ||
| Size | 22 MB | 8 MB |
| Age rating | 4+ | 4+ |
| Developer | ADVANCED FUEL DYNAMICS | SCOTT DAVID DONALD KRELL |
In-app purchases
PROFLEX Connect
No in-app purchases
Knuckle Log
- Basic$24.991 Year
- Premium$49.991 Year
- Buyer Report Unlock$35.99
Questions
Is PROFLEX Connect free?
Is Knuckle Log free?
Do PROFLEX Connect or Knuckle Log have ads?
Which is updated more often, PROFLEX Connect or Knuckle Log?
Other comparisons
