How to Buy an Express Tunnel Car Wash in 2026

Express tunnel car washes have become one of the most actively traded business types in the lower middle market. Private equity discovered the model around 2018 and hasn't stopped buying — Driven Brands, Mister Car Wash, Zips, and dozens of regional platforms are all competing for the same assets. That competition has driven multiples up, but it's also created opportunities for individual buyers who know what to look for and can move faster than institutional processes allow.

I've worked on express tunnel transactions ranging from single-site acquisitions to 15-unit portfolio deals, and the due diligence that separates a good investment from a cash incinerator is highly specific to this format. Here's what actually matters.

Membership Conversion Analysis: The Core of the Thesis

The entire express tunnel model runs on monthly unlimited wash memberships. A well-run express tunnel converts 15-25% of its retail wash customers to monthly members, and those members typically visit 3-4 times per month at an effective per-wash cost of $5-8 to the operator. Retail customers pay $12-18 per wash and come once. The economics are obvious, and the membership base is what you're really buying.

What to analyze:Request the full membership database with sign-up dates, plan tiers, churn dates, and payment method. You need to calculate monthly net membership growth (sign-ups minus cancellations) for at least 24 months. A wash with 3,000 members growing at 2% net monthly is a fundamentally different asset than one with 3,000 members that's been flat for 18 months.

Churn rateis the critical metric. Industry average for express tunnels is 6-8% monthly voluntary churn. Below 5% is exceptional and indicates strong customer satisfaction and smart plan design. Above 10% suggests pricing problems, service quality issues, or aggressive sign-up tactics that don't stick. I walked away from a 4-site deal where churn was running 12% — the seller had been offering deep discounts to inflate membership count, but customers churned as soon as the promotional rate ended.

Revenue per membertells you about plan mix. If the average member pays $25/month across three tiers ($19/$29/$39), the mix is bottom-heavy. If the average is $32, there's meaningful adoption of the premium plan. Premium plan penetration above 30% indicates an opportunity to grow revenue without adding members — which is exactly the kind of upside smart buyers look for.

Equipment Condition: The $500K-$2M Variable

Express tunnel equipment — conveyors, arches, dryers, chemical delivery systems — costs $1.5-3M to install new in a 120-foot tunnel. The condition of this equipment is arguably the most important physical due diligence item because replacement costs can wipe out years of projected cash flow.

Conveyor system:The conveyor is the backbone. A well-maintained MacNeil or AVW conveyor lasts 15-20 years. Request maintenance logs, chain replacement dates, and motor inspection records. If the conveyor is 12+ years old and the seller can't produce maintenance records, budget $300-500K for replacement within 3-5 years.

Chemical delivery systems: Modern tunnels use precise chemical metering that directly impacts cost per car. If the site is still using gravity-feed systems, the upgrade to metered delivery ($40-80K) will pay for itself within 12-18 months through chemical cost savings. Factor this into your post-acquisition CapEx plan.

Dryer systems: Blower dryers are the biggest electricity cost in an express tunnel. Older dryers can consume 150+ HP; modern variable-frequency drives cut that by 30-40%. Request 24 months of utility bills and compare to industry benchmarks of $0.40-0.60 per car for electricity. If the site is running $0.80+, outdated dryers are likely the culprit.

I always recommend hiring an independent car wash equipment inspector — not a general building inspector — to evaluate the tunnel. The due diligence cost of $5-10K is trivial relative to the risk of discovering a $400K conveyor replacement 6 months after close.

Real Estate: Own or Lease Changes Everything

Express tunnel car washes are real-estate-intensive businesses, and the real estate component often represents 40-60% of the total transaction value. Whether you're buying the real estate or leasing it fundamentally changes the deal structure and return profile.

Owned real estate transactions typically trade at 6-9x EBITDA inclusive of the land and building. The real estate component can often be separated into a sale-leaseback to reduce the equity check — some buyers acquire the business, then immediately sell the real estate to a REIT or net lease investor at a 5-6% cap rate and lease it back at favorable terms.

Leased locationstrade at lower multiples (4-6x EBITDA) but require careful lease analysis. The key terms: remaining lease duration (minimum 15 years including options for SBA financing), renewal option pricing, and whether the lease allows assignment without landlord consent. I've seen deals collapse because the landlord refused to consent to assignment or demanded a lease renegotiation as a condition — essentially capturing some of the deal economics for themselves.

Site dimensions matter for future growth. A 120-foot tunnel on a 30,000+ square foot lot with room for vacuum islands and a potential second tunnel or detail bay is worth meaningfully more than a constrained site. Express operators are increasingly adding interior detail services as an upsell, and that requires physical space.

Water Systems: The Regulatory and Operational Wildcard

An express tunnel processing 300-500 cars per day uses 30,000-50,000 gallons of water daily. Water reclaim systems that recycle 80-90% of that volume aren't optional — they're increasingly mandated by municipalities and are essential for cost control.

Reclaim system quality varies enormously. A properly maintained system produces water clean enough for all wash stages except the final rinse (which uses fresh water for a spot-free finish). A failing system produces water that smells, leaves residue, or damages the chemical process. Test the reclaim water during your site visit. If it smells like sulfur, the system needs significant work.

Water and sewer costsshould be 3-5% of revenue for a tunnel with a functioning reclaim system. If they're above 8%, either the reclaim is broken or the site doesn't have one. In either case, budget $150-300K for installation or overhaul.

Regulatory compliance is state-and municipality-specific. Some jurisdictions require discharge permits, water quality testing, and separator maintenance logs. Request all permits and compliance records. A site operating without required permits is a liability you inherit at closing — and remediation can involve six-figure costs and operational disruption.

Traffic Count Analysis: The Non-Negotiable

Express tunnels are drive-by businesses. A site's revenue ceiling is directly correlated to the traffic count on the road it sits on. This isn't opinion — it's observable in every market.

Minimum viable traffic count for an express tunnel is generally 25,000 average daily traffic (ADT) on the primary road. The sweet spot is 35,000-50,000 ADT with a signalized intersection that provides both ingress and egress. Below 20,000 ADT, even a well-run tunnel will struggle to reach the 250-300 cars per day needed to support the fixed cost structure.

You can get ADT data from your state's department of transportation website — it's public information. But don't stop there. Visit the site during weekday morning, lunch, and evening rush to observe actual traffic patterns, turning movements, and site accessibility. A 40,000 ADT road with a median barrier and no left-turn access cuts your effective trade area in half.

Competition radiusmatters as much as traffic. An express tunnel within a 3-mile radius of two competitors will split the market three ways. Check Google Maps and physically drive the trade area to identify every competitor — including new sites under construction. Municipal building permits are public record and will tell you if a competitor is building a new express tunnel nearby. I saw a buyer close on a tunnel at a 7x multiple, only to discover 60 days later that a national chain had pulled permits for a site 1.2 miles away. That's preventable with proper diligence.

The Bottom Line

Express tunnel car washes are attractive acquisitions — high margins, recurring revenue, and a model that scales. But the devil is in the specifics. Membership quality, equipment condition, real estate terms, water compliance, and traffic patterns all need independent verification. The sellers who are pricing at 7-9x know exactly what they have. Your job as a buyer is to verify that what they have is what they say it is — and to understand the CapEx cliff that might be lurking behind clean top-line numbers.

The best express tunnel acquisitions I've seen are sites with strong membership bases, well-maintained equipment, owned real estate, and room to grow throughput. If you can find that combination at 6-7x EBITDA, you have a business that can deliver 20%+ cash-on-cash returns with operational improvements. Just don't skip the diligence to get there.