Sunseeker X5

Lawn size and slope decide it. The Sunseeker X3 is rated for 800 m² and slopes up to 30%, with front-wheel drive. The Sunseeker X5 is rated for 2,000 m² and 60% slopes, with all-wheel drive. If your lawn is flat and under about 800 m², the X3 covers it; if it's bigger or has a proper bank, the X5 is the one to look at.

Some differences are less obvious. The X3 Gen 2's obstacle detection works in daylight only, while the X5 Gen 2 adds an iToF sensor for day-and-night detection. Sunseeker lists Google Assistant for the X3 but both Alexa and Google Assistant for the X5. The X5 has a slightly wider deck at 220 mm against 200 mm, and both use manual height adjustment over the same 20 mm to 60 mm range.

Much is shared. Both Gen 2 models use network RTK over built-in 4G with no antenna to install, include two years of service before a subscription is needed, and carry the same warranty terms. Neither has a published UK price, as Sunseeker sells the X series through dealers, so ask for quotes on both. Our slopes guide helps if you're unsure how steep your garden is, and the lawn size tool will measure your area.

With the X5 Gen 2, yes, after two years. The Gen 2 Sunseeker X5 gets its positioning corrections as network RTK over a built-in 4G connection, and Sunseeker bundles 24 months of that service. After that, Sunseeker's product page states that an active subscription is needed for continued use, so the fee isn't optional if you want it to keep mowing.

Sunseeker quotes the renewal price in euros on its product pages and publishes no sterling figure, so ask your dealer what it will cost in pounds. The subscription covers both the RTK corrections and the 4G link, which also runs the GPS tracking and geofence alerts.

The first-generation X5 works differently. It uses its own RTK antenna in the garden, 4G is an optional add-on, and Sunseeker doesn't require a subscription for it to mow. If a dealer still has Gen 1 stock, that's the way to avoid the fee, at the cost of a more involved installation. Gen 2 does gain day-and-night obstacle sensing, though.

Sunseeker also sells an antenna kit as an accessory, but doesn't say whether fitting one lets a Gen 2 mower keep working without paying. Until Sunseeker clarifies, assume it doesn't. When you're comparing costs over five years or so, add the subscription to blades and electricity; our running-costs calculator can help with the rest.

It should cope better than an RTK-only mower, but there are limits. Sunseeker's AONavi system on the Sunseeker X5 combines RTK satellite positioning with visual mapping from a pair of cameras (VSLAM). The idea is that the cameras help hold the mower's position where tree cover or walls weaken the satellite signal.

Sunseeker doesn't say how large a shaded area it can handle, so a lawn that's mostly under a heavy canopy is still a risk. On Gen 2, the corrections arrive over 4G, so check mobile coverage at the far end of the garden, not just by the house. Gen 1 relies on its own antenna, which needs a clear view of the sky. Our RTK signal and trees explainer covers what to look for before you buy.